Pass CFLAGS, CXXFLAGS and LDFLAGS to meson through crossfile. Fixes compilation with Meson-0.51

Author: ViliusSutkus89

3rdparty/EPMeson.cmake

@@ -74,10 +74,6 @@ function(ExternalProjectMeson EXTERNAL_PROJECT_NAME)
       # Note that if you have a single prefix with all your dependencies, you might find it easier to append to the environment variables C_INCLUDE_PATH with GCC/Clang and INCLUDE with MSVC to expand the default include path, and LIBRARY_PATH with GCC/Clang and LIB with MSVC to expand the default library search path.
       C_INCLUDE_PATH=${THIRDPARTY_PREFIX}/include
       INCLUDE=${THIRDPARTY_PREFIX}/include
-
-      CFLAGS=${MESON_CFLAGS}
-      CXXFLAGS=${MESON_CXXFLAGS}
-      LDFLAGS=${LDFLAGS}
     )
 
     set(EPM_CONFIGURE_COMMAND ${CMAKE_COMMAND} -E env ${MESON_ENV}

3rdparty/meson_cross_file.txt.in

@@ -14,6 +14,10 @@ ranlib = '@CMAKE_RANLIB@'
 
 [properties]
 needs_exe_wrapper = true
+c_args='@CFLAGS@'
+cpp_args='@CXXFLAGS@'
+c_link_args='@LDFLAGS@'
+cpp_link_args='@LDFLAGS@'
 
 [host_machine]
 system = '@MESON_SYSTEM@'