gyptest-compiler-global-settings.py fails when using the xcode-ninja generator

What steps will reproduce the problem?
1. Cherry-pick https://codereview.chromium.org/421453003/
2. Comment out the conditional test.pass_test() on line 49
3. Run ./gyptest.py -f xcode-ninja 
test/compiler-override/gyptest-compiler-global-settings.py 

Expected:
TESTGYP_FORMAT=xcode-ninja
/usr/local/opt/python/bin/python2.7 
test/compiler-override/gyptest-compiler-global-settings.py
PASSED

Actual:
  File "./pylib/gyp/generator/xcode.py", line 629, in GenerateOutput
    qualified_target)
Exception: Multiple toolsets not supported in xcode build (target 
compiler-global-settings.ninja.gyp:hello#target)

Notes:
It appears that this test is using a feature that's available in the ninja and 
make generators only. I'm not sure if the xcode-ninja generator should support 
it or if this is by design.

Original issue reported on code.google.com by tobias.h...@ableton.com on 4 Sep 2014 at 3:07

tb01070 / gyp

gyptest-compiler-global-settings.py fails when using the xcode-ninja generator #454