code review 6643050: cmd/5l: generate FreeBSD compatible ELF

cmd/5l: generate FreeBSD compatible ELF
1. correctly initialize .plt.got entries (point to the 1st entry)
2. add section .rel.plt (FreeBSD insists PLT relocs to be there)
3. put relocs of .got.plt into .rel.plt
4. set ELFOSABI_FREEBSD in ELF header

[minux1, 2012-10-09 16:02:58]

Hello rsc@golang.org (cc: golang-dev@googlegroups.com),

I'd like you to review this change to
https://code.google.com/p/go/

[minux1, 2012-10-09 16:17:53]

I guess I always choose a bad time to propose CLs. ;-)

I know we are approaching feature freeze (or already frozen?)
for Go 1.1, but i really don't want to maintain another fork for
FreeBSD/ARM.

The port is at https://codereview.appspot.com/6490119/.
AFAIK, the only remaining thing is missing ARMv5 support,
but that won't affect many, as FreeBSD-supported ARMv5
boards are mostly not capable of building Go (my test setup
has 512MiB memory so as to pass all.bash).
Adding missing sync/atomic and runtime pieces to support
ARMv5 won't be tough though.

The only problem I anticipate now is that we need a capable
FreeBSD/ARM builder (ARMv6+, preferably ARMv7, with at
least 512MiB of memory, with ~1GiB memory the builder could
run the build in tmpfs)

[rsc, 2012-10-09 16:41:05]

LGTM

[minux1, 2012-10-09 17:03:03]

*** Submitted as http://code.google.com/p/go/source/detail?r=c58647359c01 ***

cmd/5l: generate FreeBSD compatible ELF
1. correctly initialize .plt.got entries (point to the 1st entry)
2. add section .rel.plt (FreeBSD insists PLT relocs to be there)
3. put relocs of .got.plt into .rel.plt
4. set ELFOSABI_FREEBSD in ELF header

R=rsc
CC=golang-dev
http://codereview.appspot.com/6643050