[gxml] meson: disable g_ir_compiler dependency as required

[Daniel Espinosa Ortiz <despinosa src gnome org>]

commit 8c2fdc90e3e68f82ab0e4e670084f303872c8968
Author: Daniel Espinosa <esodan gmail com>
Date:   Fri Mar 2 13:05:44 2018 -0600

    meson: disable g_ir_compiler dependency as required

 gxml/meson.build | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/gxml/meson.build b/gxml/meson.build
index 5ad6456..14c55e7 100644
--- a/gxml/meson.build
+++ b/gxml/meson.build
@@ -163,7 +163,7 @@ lib = library(VERSIONED_PROJECT_NAME,
                true
        ])
 
-g_ir_compiler = find_program('g-ir-compiler')
+g_ir_compiler = find_program('g-ir-compiler', required: false)
 if g_ir_compiler.found()
 custom_target('typelib',
        command: [