CMake: "Port" the c89, c99 and c11 features

We can ignore the tests for those features and directly ask CMake
whether the compiler supports the respective language version.

Change-Id: I31cd35493443fea0c6d0b0a5e641768c3bcbe736
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>

configure.cmake

@@ -474,6 +474,17 @@ qt_feature("c++2a" PUBLIC
     CONDITION QT_FEATURE_cxx17 AND TEST_cxx2a
 )
 qt_feature_config("c++2a" QMAKE_PUBLIC_QT_CONFIG)
+qt_feature("c89"
+    LABEL "C89"
+)
+qt_feature("c99" PUBLIC
+    LABEL "C99"
+    CONDITION c_std_99 IN_LIST CMAKE_C_COMPILE_FEATURES
+)
+qt_feature("c11" PUBLIC
+    LABEL "C11"
+    CONDITION QT_FEATURE_c99 AND c_std_11 IN_LIST CMAKE_C_COMPILE_FEATURES
+)
 qt_feature("reduce_exports" PRIVATE
     LABEL "Reduce amount of exported symbols"
     CONDITION NOT WIN32 AND CMAKE_CXX_COMPILE_OPTIONS_VISIBILITY

util/cmake/configurejson2cmake.py

@@ -761,9 +761,6 @@ def get_feature_mapping():
         "alloc_malloc_h": None,
         "alloc_stdlib_h": None,
         "build_all": None,
-        "c11": None,
-        "c89": None,
-        "c99": None,
         "ccache": None,
         "compiler-flags": None,
         "cross_compile": None,