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

@@ -232,13 +232,13 @@ function(add_umf_target_compile_options name)
             PRIVATE -fPIC
                     -Wall
                     -Wextra
-                    -Wpedantic
                     -Wempty-body
                     -Wunused-parameter
                     -Wformat
                     -Wformat-security
                     -Wcast-qual
                     -Wunused-result
+                    -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)