Set SDK for Mac build to 10.6, ignore gyp/build, fixup gpu files to compile against 10.5 if needed

Review URL: http://codereview.appspot.com/5260041/



git-svn-id: http://skia.googlecode.com/svn/trunk@2470 2bbb7eff-a529-9590-31e7-b0007b416f81
3 files changed