no longer make buildrequires ghc_version explicit

ghc-zlib.spec

@@ -21,8 +21,8 @@ Summary: Haskell compression and decompression library binding
 Provides: %{name}-devel = %{version}-%{release}
 BuildRoot: %{_tmppath}/%{name}-%{version}-%{release}-root-%(%{__id_u} -n)
 ExclusiveArch:	i386 x86_64 ppc
-BuildRequires: ghc = %{ghc_version}
+BuildRequires: ghc
-BuildRequires: ghc-prof = %{ghc_version}
+BuildRequires: ghc-prof
 BuildRequires: zlib-devel
 Requires: zlib-devel
 Requires: ghc = %{ghc_version}