meson.build: enable VLA warning

variable length arrays can be dangerous, so better don't use
them at all.

Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>
Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/1819>

meson.build

@@ -13,6 +13,7 @@ cc = meson.get_compiler('c')
 
 add_project_arguments('-fno-strict-aliasing', language : 'c')
 add_project_arguments('-fvisibility=hidden', language : 'c')
+add_project_arguments('-Wvla', language: 'c')
 
 add_project_link_arguments('-fvisibility=hidden', language : 'c')
 
@@ -46,6 +47,7 @@ if cc.get_id() == 'gcc' or cc.get_id() == 'clang'
         '-Werror=address',
         '-Werror=int-to-pointer-cast',
         '-Werror=pointer-to-int-cast',
+        '-Wvla',
     ]
 else
     test_wflags = []