NaCl: Update revision in DEPS, r13739 -> r13746

This pulls in the following Native Client changes:

r13740: (dschuff) Update revision for PNaCl r13726->r13739
r13741: (dbrazdil) Implemented sysconf(), sbrk(), malloc() in MinSFI.
r13742: (dyen) Added testing for file dup/dup2 functions for irt_ext.
r13743: (jvoung) Add a checkdeps stage to the PNaCl bots/trybots as well.
r13744: (bradnelson) Only allow fastbuild to affect symbol level.
r13745: (jvoung) PNaCl: Update Subzero revision in pnacl/COMPONENT_REVISIONS
r13746: (sbc) Add creat() declaration to newlib fcntl.h

BUG=none
TEST=browser_tests and nacl_integration
CQ_EXTRA_TRYBOTS=tryserver.chromium.linux:linux_rel_precise32,linux_nacl_sdk,linux_chromium_dbg

Review URL: https://codereview.chromium.org/569133002

Cr-Commit-Position: refs/heads/master@{#294844}

DEPS

@@ -87,7 +87,7 @@ 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': '7cc5d09d0e9617c63a951b88ca50c473174b89ad', # from svn revision r13739
+  'nacl_revision': 'a0dcb51574acfe38913e5eceb16588e6a56a38a2', # from svn revision r13746
 }
 
 deps = {