[libgit2-glib] Update use of meson's python module.

[Alberto Fanjul <albfan src gnome org>]

commit 508a656756b2bc87382931b8410e2831c7da8ee5
Author: Elliott Sales de Andrade <quantum analyst gmail com>
Date:   Sun Jan 27 04:48:54 2019 -0500

    Update use of meson's python module.
    
    Also, install to arch'd dir, as that's where pygobject3 installs itself.

 libgit2-glib/meson.build | 5 +++--
 meson.build              | 2 +-
 2 files changed, 4 insertions(+), 3 deletions(-)
---
diff --git a/libgit2-glib/meson.build b/libgit2-glib/meson.build
index 3a9ec68..a6cb0c4 100644
--- a/libgit2-glib/meson.build
+++ b/libgit2-glib/meson.build
@@ -245,9 +245,10 @@ libgit2_glib_dep = declare_dependency(
 )
 
 if enable_python
-  install_data(
+  python.install_sources(
     'Ggit.py',
-    install_dir: join_paths(python.sysconfig_path('purelib'), 'gi', 'overrides'),
+    pure: false,
+    subdir: 'gi/overrides',
   )
 endif
 
diff --git a/meson.build b/meson.build
index 3b6f791..29d73ce 100644
--- a/meson.build
+++ b/meson.build
@@ -151,7 +151,7 @@ endif
 # Check for python
 enable_python = get_option('python')
 if enable_python
-  python = import('python3')
+  python = import('python').find_installation('python3')
 
   python_req = '3.2.3'