Fix X86 sigsetjmp and siglongjmp

Both exist in header android-X/arch-<arch>/usr/include/setjmp.h
already.  Add to X86 to be consistent with header and other archs
ARM/MIPS

See https://code.google.com/p/android/issues/detail?id=19851

Change-Id: I635c6c0491f5bf2aaa9013f23cb4b1bf7cb57a40

Author: Andrew Hsieh

ndk/platforms/android-9/arch-x86/lib/libc.a

@@ -761,8 +761,10 @@ sigaction
 sigaltstack
 sigblock
 siginterrupt
+siglongjmp
 sigpending
 sigprocmask
+sigsetjmp
 sigsetmask
 sigsuspend
 sigwait