[gobject-introspection] build: Install the gir-1.2 schema system-wide

[Emmanuele Bassi <ebassi src gnome org>]

commit 4ec6055394410180956b21ae49ddbcf17f5f475f
Author: Philip Withnall <philip tecnocode co uk>
Date:   Sun Nov 6 19:05:58 2016 +0000

    build: Install the gir-1.2 schema system-wide
    
    Install the schema to $(datadir)/glib-2.0/schemas, so that projects
    which depend on GLib can validate their GIR files at build or
    distribution time.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=774019

 docs/Makefile.am |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)
---
diff --git a/docs/Makefile.am b/docs/Makefile.am
index d216247..f47966d 100644
--- a/docs/Makefile.am
+++ b/docs/Makefile.am
@@ -1,3 +1,7 @@
 if ENABLE_GTK_DOC
 SUBDIRS = reference
 endif
+
+# Install the gir-1.2 schema
+schemadir = $(datadir)/gir-1.0
+dist_schema_DATA = gir-1.2.rnc