make: Fixup variable names for actions and rules.
make: Fixup variable names for actions and rules.

Action names can contain spaces, which won't work for variable
names in a Makefile.

Based on a patch from Paweł Hajdan jr <phajdan.jr@chromium.org>.
Review URL: http://codereview.chromium.org/3152004

csulmone/gyp,csulmone/gyp,csulmone/gyp,csulmone/gyp