Disable some specific warnings related with C extensions.

There are 2 warnings disabled in this commit.
cast-qual is related with dropping const specified during cast.
gnu-flexible-array-initializer notices that is the GNU extension,
used only for static const initialization of global variable.

Author: KFilipek

cmake/helpers.cmake

@@ -239,6 +239,8 @@ function(add_umf_target_compile_options name)
                     -Wformat-security
                     -Wcast-qual
                     -Wunused-result
+                    -Wno-gnu-flexible-array-initializer
+                    -Wno-cast-qual
                     $<$<CXX_COMPILER_ID:GNU>:-fdiagnostics-color=auto>)
         if(CMAKE_BUILD_TYPE STREQUAL "Release")
             target_compile_definitions(${name} PRIVATE -D_FORTIFY_SOURCE=2)

test/CMakeLists.txt

@@ -74,7 +74,8 @@ function(build_umf_test)
         # Suppress 'cast discards const qualifier' warnings. Parametrized GTEST
         # tests retrieve arguments using 'GetParam()', which applies a 'const'
         # qualifier often discarded in the test scenarios.
-        target_compile_options(${TEST_TARGET_NAME} PRIVATE -Wno-cast-qual)
+        target_compile_options(${TEST_TARGET_NAME} PRIVATE -Wno-cast-qual
+                                                           -Wno-c99-extensions)
 
         if(UMF_DEVELOPER_MODE)
             target_compile_options(${TEST_TARGET_NAME} PRIVATE -Werror)