Adding the expressions for gcc 4.5 for cross building.

Although I still have set gcc 4.4 for that, I tested with the 4.5 expression
and it cross built perfectly bison for the sheevaplug.

svn path=/nixpkgs/trunk/; revision=21463

pkgs/development/compilers/gcc-4.5/default.nix

@@ -81,7 +81,7 @@ let version = "4.5.0";
         " --disable-libmudflap " +
         " --disable-libgomp " +
         " --disable-shared" +
-        " --disable-decimal-float" # libdecnumber requires libc
+        " --disable-decimal-float" + # libdecnumber requires libc
         " --disable-multilib"
         else
         " --with-headers=${libcCross}/include" +