PR 65417 points out that the gccgo debug/elf package does not support
PPC32 relocations, which means that the cgo tool does not work
correctly.  This patch fixes that.  This is a backport of
http://golang.org/cl/7590 from the master library sources.
Bootstrapped and ran Go testsuite on x86_64-unknown-linux-gnu.
Committed to mainline.

Ian