meson.build: Silence the C99 designators warning

We use array designators for array initialization, which is a C99
extension. clang-10 warns about it, causing a build failure.

As this is a useful extension, silence the warning. This needs to be
done only if the compiler supports the -Wno-c99-designator argument,
otherwise a -Wunknown-warning-option will be generated.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>

meson.build

@@ -60,6 +60,15 @@ if cc.get_id() == 'clang'
     endif
 endif
 
+# We use C99 designated initializers for arrays as C++ has no equivalent
+# feature. Both gcc and clang support this extension, but recent
+# versions of clang generate a warning that needs to be disabled.
+if cc.has_argument('-Wno-c99-designator')
+    common_arguments += [
+        '-Wno-c99-designator',
+    ]
+endif
+
 c_arguments += common_arguments
 cpp_arguments += common_arguments