android: Attempt to fix ARMv6 cronet build with clang.

build/config/android/BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/android/config.gni")
 import("//build/config/sanitizers/sanitizers.gni")
 
 assert(is_android)
 
 # This is included by reference in the //build/config/compiler config that
@@ skipping 132 matching lines @@
   }
 
   # Manually link the libgcc.a that the cross compiler uses. This is
   # absolute because the linker will look inside the sysroot if it's not.
   libs += [
     rebase_path(android_libgcc_file),
     "c",
   ]
 
   # Clang with libc++ does not require an explicit atomic library reference.
-  if (!is_clang) {
+  if (!is_clang || (current_cpu == "arm" && arm_version == 6)) {
     libs += [ "atomic" ]
   }
 
   if (is_clang) {
     # Work around incompatibilities between bionic and clang headers.
     defines += [
       "__compiler_offsetof=__builtin_offsetof",
       "nan=__builtin_nan",
     ]
 
@@ skipping 64 matching lines @@
 
       # Avoid errors with current NDK:
       # "third_party/android_tools/ndk/toolchains/arm-linux-androideabi-4.6/prebuilt/linux-x86_64/bin/../lib/gcc/arm-linux-androideabi/4.6/include/arm_neon.h:3426:3: error: argument must be a constant"
       "-finstrument-functions-exclude-file-list=arm_neon.h",
     ]
   }
 }
 
 config("no_cygprofile_instrumentation") {
 }