If we're benchmarking 8g, use gcc -m32.
If we're benchmarking 6g, use gcc -m64.
R=golang-dev, bradfitz, minux.ma, remyoudompheng
CC=golang-dev
https://golang.org/cl/6625061
-lm must come after the source file, versions of gcc insist this strict order.
On standard compliant systems, we no longer need malloc.h for malloc.
Use pkg-config(1) to get correct glib cflags and libs.
Fix compiler warning in threadring.c and k-nucleotide.c.
R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/6198076
