Some thoughts about patch [1].

1. It would be quite enough to use just $(WINDRES) variable, set to "windres" value. It should be overridable from command line than. No need for that ifndef/ifdef mess.

2. In MinGW, windres is a part of toolchain (just like ar). I think it would be more correct to define it in gcc.lua

[1] https://bitbucket.org/premake/premake-stable/changeset/169dfa229fdb