meson: stop exporting internal wayland details

With version v1.15 the "code" option was deprecated in favour of
"private-code" or "public-code".

Before the interface symbol generated was exported (which is a bad idea
since it's internal implementation detail) and others may misuse it.

That was the case with libva approx. 1 year ago. Since then libva was
fixed, so we can finally hide it by using "private-code"

Inspired by similar xserver patch by Adam Jackson.

Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
Reviewed-by: Dylan Baker <dylan@pnwbakers.com>
Reviewed-by: Eric Engestrom <eric.engestrom@intel.com>
diff --git a/meson.build b/meson.build
index a155905..661cbba 100644
--- a/meson.build
+++ b/meson.build
@@ -1277,6 +1277,11 @@
 if with_platform_wayland
   dep_wl_scanner = dependency('wayland-scanner', native: true)
   prog_wl_scanner = find_program(dep_wl_scanner.get_pkgconfig_variable('wayland_scanner'))
+  if dep_wl_scanner.version().version_compare('>= 1.15')
+    wl_scanner_arg = 'private-code'
+  else
+    wl_scanner_arg = 'code'
+  endif
   dep_wl_protocols = dependency('wayland-protocols', version : '>= 1.8')
   dep_wayland_client = dependency('wayland-client', version : '>=1.11')
   dep_wayland_server = dependency('wayland-server', version : '>=1.11')
@@ -1292,6 +1297,7 @@
   pre_args += ['-DHAVE_WAYLAND_PLATFORM', '-DWL_HIDE_DEPRECATED']
 else
   prog_wl_scanner = []
+  wl_scanner_arg = ''
   dep_wl_protocols = null_dep
   dep_wayland_client = null_dep
   dep_wayland_server = null_dep