[tlbuild] Patches for mingw

[Karl Berry]

    -hitables.c: himktables
    -	./himktables$(EXEEXT) > $@ || { rm -f hitables.c; exit 1; }
    +hitables.c: himktables$(EXEEXT)
    +	./himktables > $@ || { rm -f hitables.c; exit 1; }

Akira, why is $(EXEEXT) a problem? It's used throughout the source tree.
Don't your Windows executables have ".exe" in the filename? --thanks, karl.