ninja win: Remove obsolete comment, and make sure cc/cxx are always overridden

Builds on discussion in https://codereview.chromium.org/321813002/.

Make sure that cc_host and cxx_host are also set to a valid compiler,
which fixes the cflags test.

R=yukawa@chromium.org
BUG=chromium:233985

Review URL: https://codereview.chromium.org/324383004

git-svn-id: http://gyp.googlecode.com/svn/trunk@1933 78cadc50-ecff-11dd-a971-7dbc132099af
Use context manager to manage OS environment in tests

This is a follow up CL for gyp r1931, just for the code cleanup.  Inspired by Nico's gyp r1893.

BUG=gyp:434
TEST=unittest
R=scottmg@chromium.org

Review URL: https://codereview.chromium.org/321183002

git-svn-id: http://gyp.googlecode.com/svn/trunk@1934 78cadc50-ecff-11dd-a971-7dbc132099af
Teach Ninja generator about 'AR' in 'make_global_settings'

With this CL, 'AR' in 'make_global_settings' can be recognized by Ninja generator, like Make generator. This makes it easier for you to share the code among host/NaCl/NDK/Emscripten build targets.

Note that 'AR.host' is not yet supported with this CL.

BUG=gyp:434
TEST=unittest
R=scottmg@chromium.org, torne@chromium.org

Review URL: https://codereview.chromium.org/321843002

git-svn-id: http://gyp.googlecode.com/svn/trunk@1935 78cadc50-ecff-11dd-a971-7dbc132099af
First crack at adding a GYP_GENERATOR for determining various things

This version reads a file to get a list of input files, then outputs
if any of the input files are contained as sources (or inputs to
actions/rules) in any targets.

R=mark@chromium.org

Patch by Scott Violet <sky@chromium.org>

Review URL: https://codereview.chromium.org/330053003

git-svn-id: http://gyp.googlecode.com/svn/trunk@1936 78cadc50-ecff-11dd-a971-7dbc132099af
Add unittest for 'LD' in 'make_global_settings'

This CL describes the current behavior with some unittests, before making Ninja generator aware of 'LD' in 'make_global_settings'. See gyp r1931 for the background.

BUG=gyp:434
TEST=unittest
R=scottmg@chromium.org

Review URL: https://codereview.chromium.org/322973006

git-svn-id: http://gyp.googlecode.com/svn/trunk@1937 78cadc50-ecff-11dd-a971-7dbc132099af
Remove unused parameters from test code.

Newer versions of the Android build system have -Wunused-params enabled
by default. Drop the many unused argc/argv parameters from test C/C++
code and also (void) a parameter in a dummy malloc function. This avoids
having to come up with a convoluted way to disable the warning flag in
every test.

BUG=gyp:433
R=thakis@chromium.org

Review URL: https://codereview.chromium.org/316163002

git-svn-id: http://gyp.googlecode.com/svn/trunk@1938 78cadc50-ecff-11dd-a971-7dbc132099af