Removes wait3(2) from LP64.

wait3(2) was removed from POSIX 2004. Keep the symbol around in LP32 for binary
compatibility, but remove the declaration in sys/wait.h.

Bug: 13935372
Change-Id: Ic715fce6781aae43b4ac6d745dc6d1e6b9914e71

libc/bionic/ndk_cruft.cpp

@@ -250,4 +250,9 @@ extern "C" int issetugid() {
   return 0;
 }
 
+// This was removed from POSIX 2004.
+extern "C" pid_t wait3(int* status, int options, struct rusage* rusage) {
+  return wait4(-1, status, options, rusage);
+}
+
 #endif