linux: include stdio.h for snprintf
linux: include stdio.h for snprintf

Fixes the following error with gcc-4.4 on Ubuntu:

  base/safe_strerror_posix.cc: In function ‘void wrap_posix_strerror_r(int (*)(int, char*, size_t), int, char*, size_t)’:
  base/safe_strerror_posix.cc:86: error: ‘snprintf’ was not declared in this scope

Patch by Joel Stanley <joel@jms.id.au>

Review URL: http://codereview.chromium.org/269046

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@28662 0039d316-1c4b-4281-b951-d872f2087c98

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