build: Add common flags to GDK backends

The common compiler and linker flags control, among other things, the
default visibility of symbols; without them, we leak symbols that ought
to be private.

gdk/broadway/meson.build

@@ -35,7 +35,12 @@ gdk_broadway_deps = [shmlib]
 libgdk_broadway = static_library('gdk-broadway',
   gdk_broadway_sources, gdkconfig, gdkenum_h,
   include_directories: [confinc, gdkinc],
-  c_args: ['-DGDK_COMPILATION', '-DG_LOG_DOMAIN="Gdk"'],
+  c_args: [
+    '-DGDK_COMPILATION',
+    '-DG_LOG_DOMAIN="Gdk"',
+    '-DG_LOG_USE_STRUCTURED=1',
+  ] + common_cflags,
+  link_args: common_ldflags,
   dependencies: [gdk_deps, gdk_broadway_deps])
 
 # gtk4-broadwayd

gdk/wayland/meson.build

@@ -99,5 +99,6 @@ libgdk_wayland = static_library('gdk-wayland',
                                   '-DGDK_COMPILATION',
                                   '-DG_LOG_DOMAIN="Gdk"',
                                   '-DG_LOG_USE_STRUCTURED=1',
-                                ],
+                                ] + common_cflags,
+                                link_args: common_ldflags,
                                 dependencies: [ gdk_deps, gdk_wayland_deps, ])

gdk/x11/meson.build

@@ -74,5 +74,6 @@ libgdk_x11 = static_library('gdk-x11',
                               '-DGDK_COMPILATION',
                               '-DG_LOG_DOMAIN="Gdk"',
                               '-DG_LOG_USE_STRUCTURED=1',
-                            ],
+                            ] + common_cflags,
+                            link_args: common_ldflags,
                             dependencies: [ gdk_deps, gdk_x11_deps, ])