build: fix MSVC UWP builds

The MSVC UWP job in CI did not actually enable UWP. Fix this and
the fallouts discovered after enabling it.

- GHA/windows: make sure to enable UWP in MSVC vcpkg UWP job.
  Use the CMake options and C flags already used for mingw-w64, but use
  `WINAPI_FAMILY_PC_APP` instead of the deprecated `WINAPI_FAMILY_APP`.
  (The former is not supported by mingw-w64, so leave it there as-is.)
  Follow-up to cb22cfca69 #14077

- GHA/windows: by default the MSVC UWP job became 2x-3x slower than
  others after actually enabling UWP. Most of it is caused by
  CMake/MSBuild automatically building full APPX containers for each
  `.exe` target. This includes 21 CMake feature detections. Each
  detection app is built into a 15MB APPX project, with code signing,
  logos, etc. Example:
    https://github.com/curl/curl/actions/runs/12056968170/job/33620610958
  Disable this overhead for curl build targets via custom
  `CMAKE_VS_GLOBALS` options. I've found no way to apply them to feature
  detection targets, so those remain slow.

- cmake: automatically enable Unicode for UWP builds. It's required.
  Also stop enabling it manually in the existing CI job.

- tests: fix `getpid()` use for Windows UWP:
  ```
  tests\server\util.c(281,21): warning C4013: 'getpid' undefined; assuming extern returning int
  ```
  Ref: https://github.com/curl/curl/actions/runs/12061215311/job/33632904249#step:11:38

- src/tool_doswin: disable `GetLoadedModulePaths()` for UWP.
  mingw-w64 UWP was okay with this, but MS SDK headers are not.
  This makes `--dump-module-paths` return empty for UWP builds.
  ```
  src\tool_doswin.c(620,3): error C2065: 'MODULEENTRY32': undeclared identifier
  src\tool_doswin.c(626,11): warning C4013: 'CreateToolhelp32Snapshot' undefined; assuming extern returning int
  src\tool_doswin.c(626,36): error C2065: 'TH32CS_SNAPMODULE': undeclared identifier
  src\tool_doswin.c(632,7): warning C4013: 'Module32First' undefined; assuming extern returning int
  ```
  Ref: https://github.com/curl/curl/actions/runs/12055081933/job/33614629930#step:9:35

- examples: fix `websocket.c` to include `winsock2.h` before `windows.h`
  to make it build with MSVC UWP:
  ```
  include\curl\curl.h(143,16): error C2061: syntax error: identifier 'curl_socket_t'
  include\curl\curl.h(143,16): error C2059: syntax error: ';'
  include\curl\curl.h(417,52): error C2146: syntax error: missing ')' before identifier 'curlfd'
  include\curl\curl.h(417,38): error C2081: 'curl_socket_t': name in formal parameter list illegal
  ```
  Ref: https://github.com/curl/curl/actions/runs/12055317910/job/33615644427#step:14:126

- GHA/windows: silence linker warning with MSVC UWP builds:
  ```
  LINK : warning LNK4075: ignoring '/INCREMENTAL' due to '/OPT:ICF' specification
  ```
  Ref: https://github.com/curl/curl/actions/runs/12055696808/job/33616629610#step:11:38

- GHA/windows: set `/INCREMENTAL:NO` for all MSVC jobs to improve
  performance a little.

- cmake: show `UWP` platform flag.

Ref: #15652
Closes #15657

.github/workflows/windows.yml

@@ -178,7 +178,7 @@ jobs:
           - { build: 'cmake'    , sys: 'mingw64', env: 'x86_64'      , tflags: ''                        , config: '-DENABLE_DEBUG=ON  -DBUILD_SHARED_LIBS=OFF -DCURL_USE_SCHANNEL=ON -DENABLE_UNICODE=ON -DENABLE_ARES=ON', type: 'Debug', name: 'schannel c-ares U' }
           - { build: 'cmake'    , sys: 'ucrt64' , env: 'ucrt-x86_64' , tflags: 'skiprun'                 , config: '-DENABLE_DEBUG=OFF -DBUILD_SHARED_LIBS=ON  -DCURL_USE_SCHANNEL=ON -DENABLE_UNICODE=ON -DENABLE_CURLDEBUG=ON', type: 'Release', name: 'schannel R TrackMemory' }
           - { build: 'cmake'    , sys: 'clang64', env: 'clang-x86_64', tflags: 'skiprun'                 , config: '-DENABLE_DEBUG=ON  -DBUILD_SHARED_LIBS=OFF -DCURL_USE_OPENSSL=ON  -DENABLE_UNICODE=OFF', type: 'Release', name: 'openssl' }
-          - { build: 'cmake'    , sys: 'ucrt64' , env: 'ucrt-x86_64' , tflags: 'skiprun'                 , config: '-DENABLE_DEBUG=OFF -DBUILD_SHARED_LIBS=ON  -DCURL_USE_SCHANNEL=ON -DENABLE_UNICODE=ON', type: 'Release', test: 'uwp', name: 'schannel' }
+          - { build: 'cmake'    , sys: 'ucrt64' , env: 'ucrt-x86_64' , tflags: 'skiprun'                 , config: '-DENABLE_DEBUG=OFF -DBUILD_SHARED_LIBS=ON  -DCURL_USE_SCHANNEL=ON', type: 'Release', test: 'uwp', name: 'schannel' }
           - { build: 'cmake'    , sys: 'mingw64', env: 'x86_64'      , tflags: 'skiprun'                 , config: '-DENABLE_DEBUG=ON  -DBUILD_SHARED_LIBS=ON  -DCURL_USE_SCHANNEL=ON -DENABLE_UNICODE=ON -DCMAKE_VERBOSE_MAKEFILE=ON', type: 'Debug', cflags: '-DCURL_SCHANNEL_DEV_DEBUG', name: 'schannel dev debug' }
           - { build: 'cmake'    , sys: 'mingw32', env: 'i686'        , tflags: 'skiprun'                 , config: '-DENABLE_DEBUG=OFF -DBUILD_SHARED_LIBS=ON  -DCURL_USE_SCHANNEL=ON -DENABLE_UNICODE=ON', type: 'Release', name: 'schannel R' }
       fail-fast: false
@@ -676,11 +676,20 @@ jobs:
         timeout-minutes: 5
         run: |
           PATH="/c/msys64/usr/bin:$PATH"
+          if [ '${{ matrix.plat }}' = 'uwp' ]; then
+            options+=' -DCMAKE_SYSTEM_NAME=WindowsStore -DCMAKE_SYSTEM_VERSION=10.0'
+            cflags='-DWINAPI_FAMILY=WINAPI_FAMILY_PC_APP'
+            ldflags='/OPT:NOREF /OPT:NOICF /APPCONTAINER:NO'
+            vsglobals=';AppxPackage=false;WindowsAppContainer=false'
+          fi
           cmake -B bld ${options} \
             "-DCMAKE_TOOLCHAIN_FILE=$VCPKG_INSTALLATION_ROOT/scripts/buildsystems/vcpkg.cmake" \
             "-DVCPKG_INSTALLED_DIR=$VCPKG_INSTALLATION_ROOT/installed" \
             '-DVCPKG_TARGET_TRIPLET=${{ matrix.arch }}-${{ matrix.plat }}' \
-            -DCMAKE_VS_GLOBALS=TrackFileAccess=false \
+            "-DCMAKE_C_FLAGS=${cflags}" \
+            "-DCMAKE_EXE_LINKER_FLAGS=/INCREMENTAL:NO ${ldflags}" \
+            "-DCMAKE_SHARED_LINKER_FLAGS=/INCREMENTAL:NO ${ldflags}" \
+            "-DCMAKE_VS_GLOBALS=TrackFileAccess=false${vsglobals}" \
             '-DCMAKE_BUILD_TYPE=${{ matrix.type }}' \
             -DCMAKE_UNITY_BUILD=ON -DCURL_TEST_BUNDLES=ON \
             -DCURL_WERROR=ON \