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