build: Simplify generation of enum files
build: Simplify generation of enum files

This fixes race conditions with parallel make, rids the world of another
stupid .stamp file, and removes the possibility of builds waiting forever
due to a similar issue to GThumb’s as mentioned here:
http://www.burtonini.com/wordpress/2012/08/02/debugging-parallelism-problems-in-make/

(I didn’t actually experience builds taking forever. I wouldn’t be here if
I had. I’d still be _there_ instead.)

MathieuDuponchelle/totem-pl-parser,pwithnall/totem-pl-parser,MathieuDuponchelle/totem-pl-parser,pwithnall/totem-pl-parser,MathieuDuponchelle/totem-pl-parser,MathieuDuponchelle/totem-pl-parser