Add BaseAddress (/BASE) support to gyp's msvs ninja generator.

BUG=https://code.google.com/p/gyp/issues/detail?id=382
TEST=BaseAddress is respected and /BASE is present in generated ninja files.
R=scottmg@chromium.org

Review URL: https://codereview.chromium.org/65983003

git-svn-id: http://gyp.googlecode.com/svn/trunk@1794 78cadc50-ecff-11dd-a971-7dbc132099af