GCC 4.6.3 gives sign comparision errors building base/logging.h.  This isn't our code, and shadowing chromium base seems like overkill, so turn off checking for sign comparison errors with gcc 4.6.
GCC 4.6.3 gives sign comparision errors building base/logging.h.  This isn't our
code, and shadowing chromium base seems like overkill, so turn off checking for
sign comparison errors with gcc 4.6.

hashashin/src,VersoBit/mod_pagespeed,webscale-networks/mod_pagespeed,pagespeed/mod_pagespeed,VersoBit/mod_pagespeed,webscale-networks/mod_pagespeed,hashashin/src,webscale-networks/mod_pagespeed,pagespeed/mod_pagespeed,pagespeed/mod_pagespeed,webscale-networks/mod_pagespeed,hashashin/src,webscale-networks/mod_pagespeed,webscale-networks/mod_pagespeed,hashashin/src,VersoBit/mod_pagespeed,hashashin/src,VersoBit/mod_pagespeed,hashashin/src,hashashin/src,VersoBit/mod_pagespeed,pagespeed/mod_pagespeed,pagespeed/mod_pagespeed,pagespeed/mod_pagespeed,VersoBit/mod_pagespeed,VersoBit/mod_pagespeed,pagespeed/mod_pagespeed,hashashin/src,webscale-networks/mod_pagespeed,webscale-networks/mod_pagespeed