[.profile] Update ccache stuff on Mac OS X

I use HomeBrew, so update the symlink dir that points to gcc for brew.

Also, Don't set a CCACHE_BASEDIR. Most the time, my builds are on
case-sensitive volumes mounted under /Volumes, but I might name them
different things. Just CCACHE it all.

Signed-off-by: Bryan Hundven <bryanhundven@gmail.com>