[gdk-pixbuf] meson: Add post-install script

[Emmanuele Bassi <ebassi src gnome org>]

commit d08de097394f327e48544d40a8fb217a0d6424af
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Sun Apr 29 18:29:49 2018 +0100

    meson: Add post-install script
    
    If we're installing gdk-pixbuf ourselves, we should generate the loaders
    cache file — unless DESTDIR is set or we're cross-compiling, in which
    case we assume that there's a packaging system hook in place to do this
    at the end of a full build.

 build-aux/post-install.sh |   17 +++++++++++++++++
 meson.build               |    7 +++++++
 2 files changed, 24 insertions(+), 0 deletions(-)
---
diff --git a/build-aux/post-install.sh b/build-aux/post-install.sh
new file mode 100644
index 0000000..40aab74
--- /dev/null
+++ b/build-aux/post-install.sh
@@ -0,0 +1,17 @@
+#!/usr/bin/bash
+
+libdir="$1"
+binary_version="$2"
+
+if [ -z "$DESTDIR" ]; then
+        mkdir -p "$libdir/gdk-pixbuf-2.0/$binary_version"
+        gdk-pixbuf-query-loaders > "$libdir/gdk-pixbuf-2.0/$binary_version/loaders.cache"
+else
+        echo "***"
+        echo "*** Warning: loaders.cache not built"
+        echo "***"
+        echo "*** You should generate this file manually on the host system"
+        echo "*** using:"
+        echo "***   gdk-pixbuf-query-loaders > $libdir/gdk-pixbuf-2.0/$binary_version/loaders.cache"
+        echo "***"
+fi
diff --git a/meson.build b/meson.build
index 956b5f5..40bbee0 100644
--- a/meson.build
+++ b/meson.build
@@ -418,3 +418,10 @@ subdir('thumbnailer')
 
 # Documentation
 subdir('docs/reference/gdk-pixbuf')
+
+if not meson.is_cross_build()
+  meson.add_install_script('build-aux/post-install.sh',
+    gdk_pixbuf_libdir,
+    gdk_pixbuf_binary_version,
+  )
+endif