Remove import of Python gyp package in gyp_main.py

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What steps will reproduce the problem?
1. On Ubuntu, install the system 'gyp' package (comes with npm/nodejs packages, 
which makes this a common problem): apt-get install gyp
2. Run ./gyp from a GYP install
3. Be surprised that it loads the gyp module from the Python interpreter 
instead of the one in pylib.

What is the expected output? What do you see instead?
The code at https://chromium.googlesource.com/external/gyp/+/master/gyp_main.py 
should be fixed so the pylib one is the default.

What version of the product are you using? On what operating system?


Please provide any additional information below.

Original issue reported on code.google.com by kjellander@chromium.org on 17 Apr 2015 at 12:16