[gtk+] build/Makefile.msvcproj: Fix cleanup

[Chun-wei Fan <fanchunwei src gnome org>]

commit 696c48d0be827e21dccaf69f59e684a1ef96d667
Author: Chun-wei Fan <fanchunwei src gnome org>
Date:   Tue Dec 20 14:39:39 2016 +0800

    build/Makefile.msvcproj: Fix cleanup
    
    When we generate the Visual Studio 2013 projects, we need to remove the
    *.vs12.sourcefiles and *.vs12.sourcefile.filters that are generated during
    the process, so that 'make distcheck' won't complain about leftover files.

 build/Makefile.msvcproj |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/build/Makefile.msvcproj b/build/Makefile.msvcproj
index 2a2dd89..a7bae54 100644
--- a/build/Makefile.msvcproj
+++ b/build/Makefile.msvcproj
@@ -128,6 +128,8 @@ $(top_builddir)/build/win32/vs12/$(1).vcxproj: Makefile
 
        $(CPP) -P - <$(top_srcdir)/build/win32/vs12/$(1).vcxprojin 
> $(top_builddir)/build/win32/vs12/$(1).vcxproj
        $(CPP) -P - <$(top_srcdir)/build/win32/vs12/$(1).vcxproj.filtersin 
> $(top_builddir)/build/win32/vs12/$(1).vcxproj.filters
+       $(RM) $(1).vs12.sourcefiles
+       $(RM) $(1).vs12.sourcefiles.filters
 
 $(top_builddir)/build/win32/vs12/$(1).vs12.headers: Makefile
        -$(RM) $(top_builddir)/build/win32/vs12/$(1).vs12.headers