[coreboot] coreinfo: use gcc wrappers

[Jordan Crouse]

Here is the patch to use the gcc wrappers in coreinfo.  Note that we
set CC and AS to ../libpayload/bin/lpgcc and ../libpayload/bin/lpas 
respectively.  This is so you can build in the svn tree without having
to install anything.  Keep that in mind.

Jordan