Update PNaCl rev for SDK to 8847 -- pulls in fix for "-pthread" bug.

DEPS

 # When adding a new dependency, please update the top-level .gitignore file
 # to list the dependency's destination directory.
 
 vars = {
   # Use this googlecode_url variable only if there is an internal mirror for it.
   # If you do not know, use the full path while defining your new deps entry.
   "googlecode_url": "http://%s.googlecode.com/svn",
   "sourceforge_url": "http://%(repo)s.svn.sourceforge.net/svnroot/%(repo)s",
   "webkit_trunk": "http://svn.webkit.org/repository/webkit/trunk",
   "nacl_trunk": "http://src.chromium.org/native_client/trunk",
@@ skipping 10 matching lines @@
   # new values.
   "nacl_toolchain_linux_x86_hash":
       "d82ef6eea6ff6ba427efa70461c2fc411d64569f",
   "nacl_toolchain_linux_x86_newlib_hash":
       "849a8cf371e17a685b9429a69474f328454b5e06",
   "nacl_toolchain_mac_x86_hash":
       "42575a21646027d52778240c03246d4534c98956",
   "nacl_toolchain_mac_x86_newlib_hash":
       "4f072a30b55ce9088ed6c6a0033dffa3a8ae301b",
   "nacl_toolchain_pnacl_linux_x86_32_hash":
-      "36d1121c16b249fe11c24b3f149a75a9da906517",
+      "5b56a39c2bb63f35c731c76fb0a28d9039f18126",
   "nacl_toolchain_pnacl_linux_x86_64_hash":
-      "01aed2db78ee87cccf7599931c87fea244e8bd54",
+      "02fb84aaf805eb33774e85de34adc1906df3c81f",
   "nacl_toolchain_pnacl_mac_x86_32_hash":
-      "333538f719ddd7742cda120cc1b70ced4d1d72ed",
+      "28fdc9843cc2c920ba5a252c8884037903daa19c",
   "nacl_toolchain_pnacl_translator_hash":
-      "6d8c5b8c0613556f39e5132d1a7b9b65e020e01e",
+      "4be9f32463a1687a385b072071c0cd8c36a69aac",
   "nacl_toolchain_pnacl_win_x86_32_hash":
-      "32c786bb095acfa0a0c5942e355af2ef03dec9dd",
+      "9f276642818cb92a2ffb63988d346376b66d3b7b",
   "nacl_toolchain_win_x86_hash":
       "85d9b16cb503a10963654803c4a4f90ea6edfff2",
   "nacl_toolchain_win_x86_newlib_hash":
       "cd4f8209a6f87d8baf21d1610928a3def4306764",
   "nacl_toolchain_revision": "8715",
-  "pnacl_toolchain_revision": "8751",
+  "pnacl_toolchain_revision": "8847",
 
   "libjingle_revision": "152",
   "libphonenumber_revision": "456",
   "libvpx_revision": "134182",
   "lss_revision": "9",
 
   # These two FFmpeg variables must be updated together.  One is used for SVN
   # checkouts and the other for Git checkouts.
   "ffmpeg_revision": "140400",
   "ffmpeg_hash": "69cc855282d18ff77e4e0a6c0de0abd539572bc8",
@@ skipping 488 matching lines @@
     "pattern": ".",
     "action": ["python", "src/build/util/lastchange.py",
                "-o", "src/build/util/LASTCHANGE"],
   },
   {
     # A change to a .gyp, .gypi, or to GYP itself should run the generator.
     "pattern": ".",
     "action": ["python", "src/build/gyp_chromium"],
   },
 ]