[gobject-introspection] build: Fix a meson build file missing in the tarball. Fixes #223

[Christoph Reiter <creiter src gnome org>]

commit fb459aa2ecc9d984a4688a6ae849864c48db57fa
Author: Christoph Reiter <reiter christoph gmail com>
Date:   Fri Aug 17 18:29:01 2018 +0200

    build: Fix a meson build file missing in the tarball. Fixes #223
    
    tests/scanner/meson.build was missing leading to:
        tests/meson.build:20:0: ERROR:  Non-existent build file 'tests/scanner/meson.build'

 tests/scanner/Makefile.am | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/tests/scanner/Makefile.am b/tests/scanner/Makefile.am
index f7075856..9da301fb 100644
--- a/tests/scanner/Makefile.am
+++ b/tests/scanner/Makefile.am
@@ -242,6 +242,7 @@ TESTS_ENVIRONMENT = env srcdir=$(srcdir) top_srcdir=$(top_srcdir) builddir=$(bui
 LOG_COMPILER = $(PYTHON) $(top_srcdir)/tests/gi-tester
 
 EXTRA_DIST += \
+       meson.build \
        $(PYTESTS) \
        Regress-1.0-C-expected                                  \
        Regress-1.0-Gjs-expected                                \