1 fix crash bug 963392, 2 update help print: the max supported gop size should be 8
Merge pull request #219 from volvet/mozilla_bug_963392_fix

fix crash bug 963392 and update the print help text.
1. support .c in makefile generator. 2. add test to check C interfaces.
Merge pull request #281 from jwwang/add_gtests

1. support .c in makefile generator. 2. add test to check C interfaces.
Regenerate target makefiles after the latest mktargets.py changes
Set CC wherever we set CXX
Merge pull request #282 from mstorsjo/update-make-for-c-test

Update makefiles after adding a C interface test