[rubygem-goocanvas] Workaround: explicitly add libpng-devel to BR

[Mamoru Tasaka]

commit e137b45fdffea02393f0185839185efebf174b05
Author: Mamoru TASAKA <mtasaka at fedoraproject.org>
Date:   Sat Aug 17 00:52:33 2013 +0900

    Workaround: explicitly add libpng-devel to BR

 rubygem-goocanvas.spec |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)
---
diff --git a/rubygem-goocanvas.spec b/rubygem-goocanvas.spec
index 6ff984d..ba9db71 100644
--- a/rubygem-goocanvas.spec
+++ b/rubygem-goocanvas.spec
@@ -19,6 +19,10 @@ Source0:	http://rubygems.org/gems/%{gem_name}-%{version}.gem
 Requires:	ruby(release)
 BuildRequires:	ruby(release)
 
+# Workaround: explicitly add libpng-devel to BR
+# so that libpng12-devel won't be pulled in
+BuildRequires:	libpng-devel >= 1.6
+
 BuildRequires:	rubygems-devel
 BuildRequires:  rubygem-cairo-devel%{?_isa}
 BuildRequires:	rubygem-gtk2-devel%{?_isa} >= %{gtkminver}