Don't pass -D_I386MACH_ALLOW_HW_INTERRUPTS explicitly in newlib build

tools/Makefile

 # Copyright (c) 2012 The Native Client Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 ##############################################################################
 # Helper script for NaCl toolchain development workflow.
 #
 # Buildbots:
 # - Sync needed sources at pinned revision and build newlib-based toolchain:
 #     make buildbot-build-with-newlib TOOLCHAINLOC=<where-to-install-the-toolchain>
@@ skipping 539 matching lines @@
         touch $@
 
 
 ##################################################################
 # newlib:
 # Builds the bare-bones library used by NativeClient applications.
 # NOTE: removes the default pthread.h to enable correct install
 # by the Native Client threads package build.
 ##################################################################
 
-NEWLIB_CFLAGS = -O2 -D_I386MACH_ALLOW_HW_INTERRUPTS -mtls-use-call
+NEWLIB_CFLAGS = -O2 -mtls-use-call
 
 BUILD/stamp-$(CROSSARCH)-newlib: | SRC/newlib BUILD newlib-libc-script
         rm -rf BUILD/build-newlib-$(CROSSARCH)
         mkdir BUILD/build-newlib-$(CROSSARCH)
         PATH=$(BUILDPATH) && export PATH && \
           cd BUILD/build-newlib-$(CROSSARCH) && \
           ../../SRC/newlib/configure \
                       --disable-libgloss \
                       --enable-newlib-iconv \
                       --enable-newlib-iconv-from-encodings=UTF-8,UTF-16LE,UCS-4LE,UTF-16,UCS-4 \
@@ skipping 545 matching lines @@
 
 
 ##################################################################
 # Remove the BUILD directory.
 # Library builds are maintained by scons.
 ##################################################################
 
 .PHONY: clean
 clean:
         rm -rf BUILD/*