Roll src/native_client/ 090f907ce..288a4a283 (2 commits).

https://chromium.googlesource.com/native_client/src/native_client.git/+log/090f907ce9b3..288a4a2832a6

$ git log 090f907ce..288a4a283 --date=short --no-merges --format='%ad %ae %s'
2016-08-31 brettw Update build, clang, buildtools.
2016-08-23 petarj [MIPS] Add BUILD.gn for mips validator

BUG=cannot build Chromium w/NaCl for MIPS

CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_chromium_dbg_32_ng
TBR=mseaborn@chromium.org

Review-Url: https://codereview.chromium.org/2303543004
Cr-Commit-Position: refs/heads/master@{#416347}

DEPS

@@ -84,7 +84,7 @@ vars = {
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling NaCl
   # and whatever else without interference from each other.
-  'nacl_revision': '090f907ce9b3d4300b6273d89598f7dfb23bbfd7',
+  'nacl_revision': '288a4a2832a61f2fe8faa1c0e1c29194afe51e0c',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling freetype-android
   # and whatever else without interference from each other.