[MIPS] Add MIPS trusted toolchain to toolchain_revisions

[MIPS] Add MIPS trusted toolchain to toolchain_revisions

Previously it was expected the devs would build their own
but this gives us the option of using a common pre-built
toolchain.

This toolchain was created using:
./tools/trusted_cross_toolchains/trusted-toolchain-creator.mipsel.debian.sh nacl_sdk

And uploaded manually using:
gsutil cp -a public-read sysroot_mips_trusted_wheezy.tgz gs://nativeclient-archive2/toolchain/b47d1a76f979dc0266392309b11dc64e7902c75a/sysroot_mips_trusted_wheezy.tgz
package_version.py archive --archive-package linux_x86/mips_trusted sysroot_mips_trusted_wheezy.tgz@https://storage.googleapis.com/nativeclient-archive2/toolchain/b47d1a76f979dc0266392309b11dc64e7902c75a/sysroot_mips_trusted_wheezy.tgz
build/package_version/package_version.py upload --upload-package linux_x86/mips_trusted --revision b47d1a76f979dc0266392309b11dc64e7902c75a
build/package_version/package_version.py  setrevision --revision-package linux_x86/mips_trusted --revision b47d1a76f979dc0266392309b11dc64e7902c75a

This package can then be installed via:
./build/package_version/package_version.py --packages linux_x86/mips_trusted sync -x

The plan is to automate this in a future CL:
https://codereview.chromium.org/1195393006/

NOTRY=true
TEST=./scons platform=mips smoke_tests
R=bradnelson@google.com

Committed: https://chromium.googlesource.com/native_client/src/native_client/+/ac2c4146f768159d04a7d16c2bba23653ec09a9e

[Sam Clegg, 2015-06-22 22:05:20]

sbc@chromium.org changed reviewers:
+ petarj@mips.com

[Sam Clegg, 2015-06-30 17:11:12]

sbc@chromium.org changed reviewers:
+ mcgrathr@chromium.org

[Sam Clegg, 2015-06-30 23:11:42]

sbc@chromium.org changed reviewers:
+ bradnelson@chromium.org

[Sam Clegg, 2015-06-30 23:11:42]

+bradnelson as I think Roland is OOO

[bradn, 2015-06-30 23:12:43]

bradnelson@google.com changed reviewers:
+ bradnelson@google.com

[bradn, 2015-06-30 23:12:43]

lgtm

[Sam Clegg, 2015-06-30 23:14:21]

The CQ bit was checked by sbc@chromium.org

[commit-bot: I haz the power, 2015-06-30 23:14:42]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1199093002/20001

[Sam Clegg, 2015-06-30 23:38:23]

The CQ bit was unchecked by sbc@chromium.org

[Sam Clegg, 2015-06-30 23:40:35]

Patchset #3 (id:40001) has been deleted

[Sam Clegg, 2015-06-30 23:41:10]

Committed patchset #3 (id:50005) manually as
ac2c4146f768159d04a7d16c2bba23653ec09a9e (presubmit successful).