meson: print c_cpp_args

Acked-by: Dylan Baker <dylan@pnwbakers.com>
Reviewed-by: Yonggang Luo <luoyonggang@gmail.com>
Signed-off-by: David Heidelberg <david.heidelberg@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/21539>

meson.build

@@ -2095,6 +2095,13 @@ summary(
   section: 'Directories'
 )
 
+summary(
+  {
+    'c_cpp_args': c_cpp_args,
+  },
+  section: 'Common C and C++ arguments'
+)
+
 summary(
   {
     'OpenGL': with_opengl,