[NaCl SDK] Add toolchain's usr/lib to create_nmf's default libpath

[NaCl SDK] Add toolchain's usr/lib to create_nmf's default libpath.

This allows libraries installed by naclports "make" commands
to be visible to create_nmf by default.

BUG=179526
R=binji@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=203977

[binji, 2013-06-03 23:48:56]

Seems a bit strange, but I guess these are the default values... and anybody who
has files in those locations almost certainly has built using naclports.

lgtm

[Sam Clegg, 2013-06-04 00:03:05]

On 2013/06/03 23:48:56, binji wrote:
> Seems a bit strange, but I guess these are the default values... and anybody
who
> has files in those locations almost certainly has built using naclports.
> 
> lgtm

Yeah.  I think the idea is that the usr/lib folders are added the default
libpath
when you first install to them, and it would be strange if the linker had a
different
set of default libpaths to create_nmf.

I could add them if and only they exist?

[Sam Clegg, 2013-06-04 16:40:12]

Committed patchset #1 manually as r203977 (presubmit successful).