build: use '-Wl,' wrapper for the -export-dynamic linker flag

Meson links with the C compiler, not the raw linker.
With clang+LLD, the bare flag would be ignored.

Signed-off-by: Greg V <greg@unrelenting.technology>

compositor/meson.build

@@ -27,7 +27,7 @@ exe_weston = executable(
 	'weston',
 	srcs_weston,
 	include_directories: include_directories('..', '../shared'),
-	link_args: [ '-export-dynamic' ],
+	link_args: [ '-Wl,-export-dynamic' ],
 	dependencies: deps_weston,
 	install: true
 )