Fix missing SYS_mmap when building Android on x86.

third_party/tcmalloc/chromium/src/malloc_hook_mmap_linux.h

 // Copyright (c) 2005, Google Inc.
 // All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 // notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
@@ skipping 36 matching lines @@
 #endif
 #else
 #include <syscall.h>
 #endif
 #include <sys/mman.h>
 #include <errno.h>
 #include "base/linux_syscall_support.h"
 
 // SYS_mmap2, SYS_munmap, SYS_mremap and __off64_t are not defined in Android.
 #if defined(__ANDROID__)
+#if defined(__NR_mmap) && !defined(SYS_mmap)
+#define SYS_mmap __NR_mmap
+#endif
 #ifndef SYS_mmap2
 #define SYS_mmap2 __NR_mmap2
 #endif
 #ifndef SYS_munmap
 #define SYS_munmap __NR_munmap
 #endif
 #ifndef SYS_mremap
 #define SYS_mremap __NR_mremap
 #endif
 typedef off64_t __off64_t;
@@ skipping 191 matching lines @@
   int result;
   if (!MallocHook::InvokeMunmapReplacement(start, length, &result)) {
     result = syscall(SYS_munmap, start, length);
   }
   return result;
 }
 
 #undef MALLOC_HOOK_HAVE_DO_MMAP64
 
 #endif  // #ifdef MALLOC_HOOK_HAVE_DO_MMAP64