runtests: support multi-target cmake, drop workarounds from CI

Support multi-target cmake builds via `CURL_DIRSUFFIX` env. For example:
`export CURL_DIRSUFFIX=Debug/`.

Multi-target generators place their output to `src/<subdir>/`,
`lib/<subdir>/`, `tests/server/<subdir>`, `tests/libtest/<subdir>` and
`tests/unit/<subdir>/` by default. Before this patch, `runtests.pl`
couldn't run on such builds because it expected the binaries under the
their `<subdir>`-less directories. This patch allows to set such subdir
and make `runtests.pl` find the binaries. In CI we use multi-target
builds with tests for MSVC. It also helps Xcode-generator builds, though
in CI we don't have such job running tests.

There may be better solutions to configure this, but passing a custom
value to `runtests.pl` including its subprocesses is somewhat tricky.
The reason the configuration value expects the slash at the end is
because MSYS is automagically expanding the env to a (wrong) absolute
path if the slash is in the front.

Also:
- drop the `-DCMAKE_RUNTIME_OUTPUT_DIRECTORY_*=` workaround from CI.
- replace `resolve` references in tests with a new `%RESOLVE` variable.
  It didn't use a filename extension before. After this patch it uses
  `exe_ext('TOOL')`. I'm not sure if this is the correct choice vs.
  `exe_ext('SRV')`.
- fix `-c` option format in manual.
- fix some whitespace.

Note, in CI we still tweak `CMAKE_RUNTIME_OUTPUT_DIRECTORY_*` in jobs
which share steps between `./configure` and cmake. It's easier that way.

Ref: #15000
Cherry-picked from #16394

Closes #16452

.github/workflows/windows.yml

@@ -827,8 +827,6 @@ jobs:
               -DCMAKE_EXE_LINKER_FLAGS="-INCREMENTAL:NO ${ldflags}" \
               -DCMAKE_SHARED_LINKER_FLAGS="-INCREMENTAL:NO ${ldflags}" \
               -DCMAKE_VS_GLOBALS="TrackFileAccess=false${vsglobals}" \
-              -DCMAKE_RUNTIME_OUTPUT_DIRECTORY_DEBUG= \
-              -DCMAKE_RUNTIME_OUTPUT_DIRECTORY_RELEASE= \
               -DCMAKE_UNITY_BUILD=ON -DCURL_TEST_BUNDLES=ON \
               -DCURL_WERROR=ON \
               -DBUILD_SHARED_LIBS=OFF \
@@ -860,8 +858,8 @@ jobs:
         run: |
           PATH=/usr/bin find . \( -name '*.exe' -o -name '*.dll' -o -name '*.lib' \) -exec file '{}' \;
           if [ '${{ matrix.plat }}' != 'uwp' ]; then  # Missing: ucrtbased.dll, VCRUNTIME140D.dll, VCRUNTIME140D_APP.dll
-            PATH="$PWD/bld/lib:$PATH"
-            bld/src/curl.exe --disable --version
+            PATH="$PWD/bld/lib/${{ matrix.type }}:$PATH"
+            'bld/src/${{ matrix.type }}/curl.exe' --disable --version
           fi
 
       - name: 'build tests'
@@ -896,13 +894,14 @@ jobs:
         if: ${{ matrix.tflags != 'skipall' && matrix.tflags != 'skiprun' }}
         timeout-minutes: 10
         run: |
+          export CURL_DIRSUFFIX='${{ matrix.type }}/'
           export TFLAGS='-j8 ~WebSockets ~SCP ~612 ${{ matrix.tflags }}'
           if [[ '${{ matrix.install }}' = *'libssh2[core,zlib]'* ]]; then
             TFLAGS+=' ~SFTP'
           elif [[ '${{ matrix.install }}' = *'libssh '* ]]; then
             TFLAGS+=' ~614'  # 'SFTP pre-quote chmod' SFTP, pre-quote, directory
           fi
-          PATH="$PWD/bld/lib:$PATH:/c/Program Files (x86)/stunnel/bin:/c/Program Files/OpenSSH-Win64"
+          PATH="$PWD/bld/lib/${{ matrix.type }}:$PATH:/c/Program Files (x86)/stunnel/bin:/c/Program Files/OpenSSH-Win64"
           PATH="/c/msys64/usr/bin:$PATH"
           cmake --build bld --config '${{ matrix.type }}' --target test-ci