Linux: build with clang out-of-the-box, without need

src/trusted/service_runtime/linux/nacl_bootstrap.gyp

 # 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.
 
 {
   'includes': [
     '../../../../build/common.gypi',
   ],
   'conditions': [
     ['target_arch=="x64"', {
@@ skipping 48 matching lines @@
       'type': 'static_library',
       'product_dir': '<(SHARED_INTERMEDIATE_DIR)/nacl_bootstrap',
       'hard_depencency': 1,
       'include_dirs': [
         '..',
       ],
       'sources': [
         'nacl_bootstrap.c',
       ],
       'cflags': [
+        # Prevent llvm-opt from replacing my_bzero with a call
+        # to memset.
+        '-fno-builtin',
         # The tiny standalone bootstrap program is incompatible with
         # -fstack-protector, which might be on by default.  That switch
         # requires using the standard libc startup code, which we do not.
         '-fno-stack-protector',
         # We don't want to compile it PIC (or its cousin PIE), because
         # it goes at an absolute address anyway, and because any kind
         # of PIC complicates life for the x86-32 assembly code.  We
         # append -fno-* flags here instead of using a 'cflags!' stanza
         # to remove -f* flags, just in case some system's compiler
         # defaults to using PIC for everything.
         '-fno-pic', '-fno-PIC',
         '-fno-pie', '-fno-PIE',
       ],
       'cflags!': [
         # TODO(glider): -fasan is deprecated.
         '-fasan',
         '-faddress-sanitizer',
         '-w',
         # We filter these out because release_extra_cflags or another
         # such thing might be adding them in, and those options wind up
         # coming after the -fno-stack-protector we added above.
         '-fstack-protector',
         '-fstack-protector-all',
         '-fprofile-generate',
         '-finstrument-functions',
       ],
       'conditions': [
         ['clang==1', {
           'cflags': [
-            # Prevent llvm-opt from replacing my_bzero with a call
-            # to memset
-            '-ffreestanding',
-            # But make its <limits.h> still work!
-            '-U__STDC_HOSTED__', '-D__STDC_HOSTED__=1',
             # TODO(bbudge) Remove this when Clang supports -fno-pic.
             '-Qunused-arguments',
           ],
         }],
       ],
     },
     {
       'target_name': 'nacl_bootstrap_raw',
       'type': 'none',
       # This magical flag tells Gyp that the dependencies of this target
@@ skipping 89 matching lines @@
         'inputs': ['nacl_bootstrap_munge_phdr.py',
                    '<(PRODUCT_DIR)/nacl_bootstrap_munge_phdr',
                    '<(PRODUCT_DIR)/nacl_bootstrap_raw'],
         'outputs': ['<(PRODUCT_DIR)/nacl_helper_bootstrap'],
         'message': 'Munging ELF program header',
         'action': ['python', '<@(_inputs)', '<@(_outputs)']
       }],
     },
   ],
 }