Don't include TargetConditionals.h when building for android.

build/build_config.h

 // Copyright (c) 2012 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.
 
 // This file adds defines about the platform we're currently building on.
 //  Operating System:
 //    OS_WIN / OS_MACOSX / OS_LINUX / OS_POSIX (MACOSX or LINUX) / OS_NACL
 //  Compiler:
 //    COMPILER_MSVC / COMPILER_GCC
 //  Processor:
 //    ARCH_CPU_X86 / ARCH_CPU_X86_64 / ARCH_CPU_X86_FAMILY (X86 or X86_64)
 //    ARCH_CPU_32_BITS / ARCH_CPU_64_BITS
 
 #ifndef BUILD_BUILD_CONFIG_H_
 #define BUILD_BUILD_CONFIG_H_
 
-#if defined(__APPLE__)
-#include <TargetConditionals.h>
-#endif
-
 // A set of macros to use for platform detection.
 #if defined(__native_client__)
 // __native_client__ must be first, so that other OS_ defines are not set.
 #define OS_NACL 1
 #elif defined(ANDROID)
 #define OS_ANDROID 1
 #elif defined(__APPLE__)
+// only include TargetConditions after testing ANDROID as some android builds
+// on mac don't have this header available and it's not needed unless the target
+// is really mac/ios.
+#include <TargetConditionals.h>
 #define OS_MACOSX 1
 #if defined(TARGET_OS_IPHONE) && TARGET_OS_IPHONE
 #define OS_IOS 1
 #endif  // defined(TARGET_OS_IPHONE) && TARGET_OS_IPHONE
 #elif defined(__linux__)
 #define OS_LINUX 1
 // include a system header to pull in features.h for glibc/uclibc macros.
 #include <unistd.h>
 #if defined(__GLIBC__) && !defined(__UCLIBC__)
 // we really are using glibc, not uClibc pretending to be glibc
@@ skipping 112 matching lines @@
 #if defined(OS_ANDROID)
 // The compiler thinks std::string::const_iterator and "const char*" are
 // equivalent types.
 #define STD_STRING_ITERATOR_IS_CHAR_POINTER
 // The compiler thinks base::string16::const_iterator and "char16*" are
 // equivalent types.
 #define BASE_STRING16_ITERATOR_IS_CHAR16_POINTER
 #endif
 
 #endif  // BUILD_BUILD_CONFIG_H_