[ccache] Unsupported compiler option

[devsk]

Can we please fix this simple thing:

# egrep "Compiler option -E is unsupported|unsupported compiler option" 
/var/tmp/ccache/logfile-for-ccache.log |wc -l
4096

# grep "Compiler option -E is unsupported" 
/var/tmp/ccache/logfile-for-ccache.log |wc -l
2048

Basically, when gcc is invoked specifically for preprocessing, ccache should not 
increment its "unsupported" counter. Its unnecessarily creating confusion by 
showing thousands of files as "unsupported compiler option", when it really is 
not supposed to be doing anything for it.

Thanks,
-devsk