cmake: add CURL_PATCHSTAMP configuration variable, test in CI

Also:
- INSTALL-CMAKE.md: alpha sort.

Closes #20576

.github/workflows/linux.yml

@@ -166,7 +166,7 @@ jobs:
           - name: 'awslc'
             install_packages: libidn2-dev
             install_steps: awslc
-            generate: -DOPENSSL_ROOT_DIR=/home/runner/awslc -DUSE_ECH=ON -DCMAKE_UNITY_BUILD=OFF -DCURL_DROP_UNUSED=ON
+            generate: -DOPENSSL_ROOT_DIR=/home/runner/awslc -DUSE_ECH=ON -DCMAKE_UNITY_BUILD=OFF -DCURL_DROP_UNUSED=ON -DCURL_PATCHSTAMP=test-patch
 
           - name: 'boringssl'
             install_steps: boringssl pytest

CMakeLists.txt

@@ -149,6 +149,10 @@ else()
   set(CURL_OS "\"${CMAKE_SYSTEM_NAME}\"")
 endif()
 
+if(CURL_PATCHSTAMP)
+  set(CURL_PATCHSTAMP "\"${CURL_PATCHSTAMP}\"")
+endif()
+
 set(LIB_NAME "libcurl")
 set(EXE_NAME "curl")
 

docs/INSTALL-CMAKE.md

@@ -239,6 +239,7 @@ target_link_libraries(my_target PRIVATE CURL::libcurl)
 - `CURL_DEFAULT_SSL_BACKEND`:               Override default TLS backend in MultiSSL builds.
                                             Accepted values in order of default priority:
                                             `wolfssl`, `gnutls`, `mbedtls`, `openssl`, `schannel`, `rustls`
+- `CURL_DROP_UNUSED`:                       Drop unused code and data from built binaries. Default: `OFF`
 - `CURL_ENABLE_EXPORT_TARGET`:              Enable CMake export target. Default: `ON`
 - `CURL_HIDDEN_SYMBOLS`:                    Hide libcurl internal symbols (=hide all symbols that are not officially external). Default: `ON`
 - `CURL_LIBCURL_SOVERSION`:                 Enable libcurl SOVERSION. Default: `ON` for supported platforms
@@ -246,7 +247,7 @@ target_link_libraries(my_target PRIVATE CURL::libcurl)
 - `CURL_LIBCURL_VERSIONED_SYMBOLS_PREFIX`:  Override default versioned symbol prefix. Default: `<TLS-BACKEND>_` or `MULTISSL_`
 - `CURL_LINT`:                              Run lint checks while building. Default: `OFF`
 - `CURL_LTO`:                               Enable compiler Link Time Optimizations. Default: `OFF`
-- `CURL_DROP_UNUSED`:                       Drop unused code and data from built binaries. Default: `OFF`
+- `CURL_PATCHSTAMP`:                        Set security patch string for `curl -V`/`curl --version` output.
 - `CURL_STATIC_CRT`:                        Build libcurl with static CRT with MSVC (`/MT`) (requires UCRT, static libcurl or no curl executable). Default: `OFF`
 - `CURL_TARGET_WINDOWS_VERSION`:            Minimum target Windows version as hex string.
 - `CURL_WERROR`:                            Turn compiler warnings into errors. Default: `OFF`

lib/curl_config-cmake.h.in

@@ -330,6 +330,9 @@
 /* BoringSSL version */
 #cmakedefine CURL_BORINGSSL_VERSION ${CURL_BORINGSSL_VERSION}
 
+/* Patch stamp */
+#cmakedefine CURL_PATCHSTAMP ${CURL_PATCHSTAMP}
+
 /* Define to 1 if you have the <ifaddrs.h> header file. */
 #cmakedefine HAVE_IFADDRS_H 1