x86 has an assembler bcopy implementation.

Change-Id: I4ed7af3c5b104f86550120401f773150c460f37b
diff --git a/libc/bionic/ndk_cruft.cpp b/libc/bionic/ndk_cruft.cpp
index 341ba01..28d6355 100644
--- a/libc/bionic/ndk_cruft.cpp
+++ b/libc/bionic/ndk_cruft.cpp
@@ -235,11 +235,15 @@
   return signal(signum, handler);
 }
 
+#if !defined(__i386__)
 // This was removed from POSIX 2008.
 #undef bcopy
 extern "C" void bcopy(const void* src, void* dst, size_t n) {
   memcpy(dst, src, n);
 }
+#else
+// x86 has an assembler implementation.
+#endif
 
 // sysv_signal() was never in POSIX.
 extern sighandler_t _signal(int signum, sighandler_t handler, int flags);