[gnome-builder] build: Fix installing meson plugin

[Patrick Griffis <pgriffis src gnome org>]

commit 088180d1b1c803dc69f09b1299e68aab6e4a3dd9
Author: Patrick Griffis <tingping tingping se>
Date:   Sat Oct 29 20:41:17 2016 -0400

    build: Fix installing meson plugin

 plugins/Makefile.am |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/plugins/Makefile.am b/plugins/Makefile.am
index ee1f04f..7828dac 100644
--- a/plugins/Makefile.am
+++ b/plugins/Makefile.am
@@ -25,6 +25,7 @@ SUBDIRS = \
        jedi \
        jhbuild \
        mingw \
+       meson \
        project-tree \
        python-gi-imports-completion \
        python-pack \