[gtksourceview] build: add missing git.mk include

[Sébastien Wilmet <swilmet src gnome org>]

commit 958dcb3fd91f5d008cef6a20656beaa9c3c04a72
Author: Sébastien Wilmet <swilmet gnome org>
Date:   Sat Mar 26 19:19:20 2016 +0100

    build: add missing git.mk include

 build/win32/Makefile.am |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/build/win32/Makefile.am b/build/win32/Makefile.am
index 45a8546..26013a5 100644
--- a/build/win32/Makefile.am
+++ b/build/win32/Makefile.am
@@ -37,3 +37,5 @@ gen-enums.bat: $(top_srcdir)/build/win32/gen-enums.batin enum.headers
        $(RM) enum.headers
 
 DISTCLEANFILES = $(GENERATED_ITEMS)
+
+-include $(top_srcdir)/git.mk