Meta/CMake: Use simple string match to find relevant vcpkg triplets

Previously, the build would fail if the CMake source directory
contained regex special characters.

Meta/CMake/vcpkg/generate_vcpkg_toolchain_variables.cmake

@@ -29,7 +29,8 @@ if (NOT DEFINED CACHE{VCPKG_TARGET_TRIPLET} AND NOT DEFINED CACHE{VCPKG_HOST_TRI
     endif()
 
     # And then, only tweak settings if the triplets are ours
-    if (NOT VCPKG_OVERLAY_TRIPLETS MATCHES "^${CMAKE_CURRENT_SOURCE_DIR}")
+    string(FIND "${VCPKG_OVERLAY_TRIPLETS}" "${CMAKE_CURRENT_SOURCE_DIR}" VCPKG_OVERLAY_TRIPLETS_MATCH)
+    if (VCPKG_OVERLAY_TRIPLETS_MATCH EQUAL -1)
         return()
     endif()