Revise unittest for 'AR' in 'make_global_settings'

This is a follow up CL for r1931 and r1935. This is just a revise of a unittest and does not changes existing functionality.

It turned out that we need to specify GYP_CROSSCOMPILE=1 to test 'AR'/'AR.host'
properly. Expected results, which correspond to the current behavior atually, are updated accordingly.

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

Review URL: https://codereview.chromium.org/336953002

git-svn-id: http://gyp.googlecode.com/svn/trunk@1940 78cadc50-ecff-11dd-a971-7dbc132099af
Teach Ninja generator about 'LD'/'LD.host' specified in 'make_global_settings_ld'.

With this CL, Ninja generator starts recognizing 'LD'/'LD.host' specified in 'make_global_settings', like Make generator.  This makes it easier for you to share the code among host/NaCl/NDK/Emscripten build targets.

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

Review URL: https://codereview.chromium.org/335443007

git-svn-id: http://gyp.googlecode.com/svn/trunk@1941 78cadc50-ecff-11dd-a971-7dbc132099af
Teach Ninja generator about 'AR.host' specified in 'make_global_settings'.

With this CL, Ninja generator starts recognizing 'AR.host' specified in 'make_global_settings', like Make generator.

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

Review URL: https://codereview.chromium.org/333353002

git-svn-id: http://gyp.googlecode.com/svn/trunk@1942 78cadc50-ecff-11dd-a971-7dbc132099af