NaCl: Update revision in DEPS, 58c9abe -> fea15c4

This pulls in the following Native Client changes:

f02226b: (bbudge@chromium.org) Disable mmap_unittest.cc tests on Windows 64 in Debug...
6bc00f6: (dschuff@chromium.org) Update upstream compiler_rt to HEAD and use official git mirror
55d212c: (phosek@chromium.org) Updates the tools Makefile to work with Git
ccc9c66: (shyamsundarr@chromium.org) Add all remaining avx2 instructions except vgather.
9595661: (jfb@chromium.org) Enable -Werror for LLVM build
aa51c35: (pcc@google.com) Disable -flto when compiling nacl_bootstrap_lib.
476c662: (jfb@chromium.org) PNaCl: Update Subzero and LLVM revision in pnacl/COMPONENT_REVISIONS
2f388a0: (dschuff@chromium.org) Enable SCons testing of arm-nacl-clang on the bots
fea15c4: (bbudge@chromium.org) Disable mmap_unittest.cc tests on Windows 64 in Debug...

BUG=none
TEST=browser_tests and nacl_integration
CQ_EXTRA_TRYBOTS=tryserver.chromium.linux:linux_rel_precise32,linux_arm_compile,linux_nacl_sdk_build

Review URL: https://codereview.chromium.org/867463008

Cr-Commit-Position: refs/heads/master@{#314020}

DEPS

@@ -94,7 +94,7 @@ 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': '58c9abefa29b489e4b40fc581451bdb7d2984372',
+  'nacl_revision': 'fea15c4',
 }
 
 # Only these hosts are allowed for dependencies in this DEPS file.