Fix bug with checkdeps on OS X and git.
Fix bug with checkdeps on OS X and git.

Basically, checkdeps on OS X and git is a no-op without this fix, as
OS X (almost always) has a case-insensitive file system and checkdeps
does case-sensitive comparisons.

BUG=none
TEST=ran checkdeps before/after

Review URL: http://codereview.chromium.org/3356015

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@59066 0039d316-1c4b-4281-b951-d872f2087c98

adobe/chromium,gavinp/chromium,adobe/chromium,yitian134/chromium,Crystalnix/house-of-life-chromium,Crystalnix/house-of-life-chromium,gavinp/chromium,yitian134/chromium,Crystalnix/house-of-life-chromium,Crystalnix/house-of-life-chromium,ropik/chromium,ropik/chromium,Crystalnix/house-of-life-chromium,gavinp/chromium,yitian134/chromium,ropik/chromium,gavinp/chromium,adobe/chromium,gavinp/chromium,ropik/chromium,Crystalnix/house-of-life-chromium,yitian134/chromium,gavinp/chromium,yitian134/chromium,adobe/chromium,yitian134/chromium,ropik/chromium,adobe/chromium,gavinp/chromium,Crystalnix/house-of-life-chromium,Crystalnix/house-of-life-chromium,gavinp/chromium,ropik/chromium,adobe/chromium,adobe/chromium,Crystalnix/house-of-life-chromium,adobe/chromium,gavinp/chromium,ropik/chromium,yitian134/chromium,Crystalnix/house-of-life-chromium,ropik/chromium,yitian134/chromium,adobe/chromium,Crystalnix/house-of-life-chromium,adobe/chromium,adobe/chromium,gavinp/chromium,ropik/chromium,yitian134/chromium,yitian134/chromium