Remove perf_event_open.

This was accidentally added at a time when you couldn't add a constant
to <syscall.h> without generating an assembly stub! (You no longer need
to add the constants at all.)

Bug: 11156955
Change-Id: I053c17879138787976c744a5ecf7d30ee51dc48f

libc/arch-x86_64/syscalls/perf_event_open.S

@@ -1,17 +0,0 @@
-/* Generated by gensyscalls.py. Do not edit. */
-
-#include <private/bionic_asm.h>
-
-ENTRY(perf_event_open)
-    movq    %rcx, %r10
-    movl    $__NR_perf_event_open, %eax
-    syscall
-    cmpq    $-MAX_ERRNO, %rax
-    jb      1f
-    negl    %eax
-    movl    %eax, %edi
-    call    __set_errno
-    orq     $-1, %rax
-1:
-    ret
-END(perf_event_open)