[mutter] plugins/Makefile.am: Don't fail when trying to remove nonexisting file

[Jasper St. Pierre <jstpierre src gnome org>]

commit 22c13b3144e0aa348ac61ae34782b0028aba59c1
Author: Jonas Ådahl <jadahl gmail com>
Date:   Tue Jan 20 00:32:27 2015 +0800

    plugins/Makefile.am: Don't fail when trying to remove nonexisting file
    
    https://bugzilla.gnome.org/show_bug.cgi?id=743189

 src/compositor/plugins/Makefile.am |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/src/compositor/plugins/Makefile.am b/src/compositor/plugins/Makefile.am
index 0725991..38988d0 100644
--- a/src/compositor/plugins/Makefile.am
+++ b/src/compositor/plugins/Makefile.am
@@ -24,8 +24,8 @@ pkglib_LTLIBRARIES = default.la
 # (There is no way to stop libtool generating static libs locally, and we
 # cannot do this globally because of libmutter-private.so).
 install-exec-hook:
-       -rm $(DESTDIR)$(pkglibdir)/*.a
-       -rm $(DESTDIR)$(pkglibdir)/*.la
+       -rm -f $(DESTDIR)$(pkglibdir)/*.a
+       -rm -f $(DESTDIR)$(pkglibdir)/*.la
 
 # Since we removed the .la file, 'make uninstall' doesn't work properly,
 # since it counts on libtool to remove the .la files, so just kill the