Revert GYP_PARALLEL-on-by-default (r1666).

Tests fail on the bots, see http://crbug.com/154205

R=scottmg@chromium.org

Review URL: https://codereview.chromium.org/18629005

git-svn-id: http://gyp.googlecode.com/svn/trunk@1671 78cadc50-ecff-11dd-a971-7dbc132099af
fix +x on gyp_main.py

Should fix -regen tests on Mac under make.

R=thakis@chromium.org

Review URL: https://codereview.chromium.org/18402004

git-svn-id: http://gyp.googlecode.com/svn/trunk@1672 78cadc50-ecff-11dd-a971-7dbc132099af