Improve pointer hash function to include all bits

Improve pointer hash function to include all bits

The hashtab pointer hash function is not very good. It throws most of the
bits in the pointer away.

This changes pointer_hash to use the mix code from jhash function that mixes
all the bits on the pointer and makes them dependent on each other, before doing
the modulo.

libiberty/:

2013-04-22  Andi Kleen <ak@linux.intel.com>

	* hashtab.c (hash_pointer): Move to end of file and reimplement.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@198171 138bc75d-0d04-0410-961f-82ee72b054a4