[gtk/gtk-3-24: 1/2] Require Harfbuzz only for Wayland and X11 backends.

[Chun-wei Fan <fanchunwei src gnome org>]

commit e169e2bdd5d9e22190745dda5bbc382cc4e43d8e
Author: John Ralls <jralls ceridwen us>
Date:   Sat Jun 22 10:51:43 2019 -0700

    Require Harfbuzz only for Wayland and X11 backends.
    
    Fixes https://gitlab.gnome.org/GNOME/gtk/issues/1968

 meson.build | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/meson.build b/meson.build
index f7b28f5ad4..36913b3f04 100644
--- a/meson.build
+++ b/meson.build
@@ -471,7 +471,8 @@ if cc.get_id() == 'msvc' and not harfbuzz_dep.found()
   endif
 endif
 
-if not harfbuzz_dep.found()
+require_harfbuzz = wayland_enabled or x11_enabled
+if require_harfbuzz and not harfbuzz_dep.found()
   harfbuzz_dep   = dependency('harfbuzz', version: '>= 0.9', required: false,
                               fallback: ['harfbuzz', 'libharfbuzz_dep'])
 endif