Port a lot more code to AARCH64

- Introduce epoll_pwait()
- Rewrite -ftrapv and ffs() libraries in C code
- Use more FreeBSD code in math function library
- Get significantly more tests passing on qemu-aarch64
- Fix many Musl long double functions that were broken on AARCH64

libc/calls/pledge-linux.c

@@ -608,6 +608,7 @@ static const uint16_t kPledgeStdio[] = {
 #endif                             //
     __NR_linux_msync,              //
     __NR_linux_mmap | NOEXEC,      //
+    __NR_linux_mlock,              //
     __NR_linux_mremap,             //
     __NR_linux_munmap,             //
     __NR_linux_mincore,            //