Merge topic 'msvc-isystem' into release-3.22

3a8b6653dc MSVC: Use -external:I flag without space to support Clang tools

Acked-by: Kitware Robot <[email protected]>
Merge-request: !6855

Modules/Compiler/MSVC-C.cmake

@@ -77,6 +77,6 @@ endif()
 
 # The `/external:I` flag was made non-experimental in 19.29.30036.3.
 if (CMAKE_C_COMPILER_VERSION VERSION_GREATER_EQUAL 19.29.30036.3)
-  set(CMAKE_INCLUDE_SYSTEM_FLAG_C "-external:I ")
+  set(CMAKE_INCLUDE_SYSTEM_FLAG_C "-external:I")
   set(_CMAKE_INCLUDE_SYSTEM_FLAG_C_WARNING "-external:W0 ")
 endif ()

Modules/Compiler/MSVC-CXX.cmake

@@ -84,6 +84,6 @@ endif()
 
 # The `/external:I` flag was made non-experimental in 19.29.30036.3.
 if (CMAKE_CXX_COMPILER_VERSION VERSION_GREATER_EQUAL 19.29.30036.3)
-  set(CMAKE_INCLUDE_SYSTEM_FLAG_CXX "-external:I ")
+  set(CMAKE_INCLUDE_SYSTEM_FLAG_CXX "-external:I")
   set(_CMAKE_INCLUDE_SYSTEM_FLAG_CXX_WARNING "-external:W0 ")
 endif ()