Add missing BuildRequires on gcc

make: gcc: Command not found

References: https://bugzilla.redhat.com/show_bug.cgi?id=1603841
Signed-off-by: Igor Gnatenko <ignatenkobrain@fedoraproject.org>

dumpet.spec

@@ -5,6 +5,7 @@ Summary:        A tool to dump and debug bootable CD images
 License:        GPLv2+
 Group:          Development/Tools
 URL:            https://fedorahosted.org/dumpet/
+BuildRequires:  gcc
 BuildRequires:  popt-devel pkgconfig libxml2-devel git
 
 Source0:        https://fedorahosted.org/releases/d/u/dumpet/dumpet-%{version}.tar.bz2