Simplify genex expressions

Simplifications:
- `COMPILE_LANGUAGE` accepts comma-separated list since 3.15

Change-Id: I4af316a463b5771bf5b37a6b4d77e41adba60977
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>
(cherry picked from commit 51dc4cd)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
(cherry picked from commit cedaf89)

cmake/QtInternalTargets.cmake

@@ -77,7 +77,7 @@ function(qt_internal_set_warnings_are_errors_flags target target_scope)
     # Apparently qmake only adds -Werror to CXX and OBJCXX files, not C files. We have to do the
     # same otherwise MinGW builds break when building 3rdparty\md4c\md4c.c (and probably on other
     # platforms too).
-    set(cxx_only_genex "$<OR:$<COMPILE_LANGUAGE:CXX>,$<COMPILE_LANGUAGE:OBJCXX>>")
+    set(cxx_only_genex "$<COMPILE_LANGUAGE:CXX,OBJCXX>")
     set(final_condition_genex "$<AND:${warnings_are_errors_enabled_genex},${cxx_only_genex}>")
     set(flags_generator_expression "$<${final_condition_genex}:${flags}>")
 

cmake/QtPrecompiledHeadersHelpers.cmake

@@ -3,7 +3,7 @@
 
 function(qt_update_precompiled_header target precompiled_header)
     if (precompiled_header AND BUILD_WITH_PCH)
-        set_property(TARGET "${target}" APPEND PROPERTY "PRECOMPILE_HEADERS" "$<$<OR:$<COMPILE_LANGUAGE:CXX>,$<COMPILE_LANGUAGE:OBJCXX>>:${precompiled_header}>")
+        set_property(TARGET "${target}" APPEND PROPERTY "PRECOMPILE_HEADERS" "$<$<COMPILE_LANGUAGE:CXX,OBJCXX>:${precompiled_header}>")
     endif()
 endfunction()