Improve locks and signals

- Introduce fast spinlock API
- Double rand64() perf w/ spinlock
- Improve raise() on New Technology
- Support gettid() across platforms
- Implement SA_NODEFER on New Technology
- Move the lock intrinsics into LIBC_INTRIN
- Make SIGTRAP recoverable on New Technology
- Block SIGCHLD in wait4() on New Technology
- Add threading prototypes for XNU and FreeBSD
- Rewrite abort() fixing its minor bugs on XNU/NT
- Shave down a lot of the content in libc/bits/bits.h
- Let signal handlers modify CPU registers on New Technology

libc/time/clockstonanos.internal.h

@@ -0,0 +1,15 @@
+#ifndef COSMOPOLITAN_LIBC_TIME_CLOCKSTONANOS_INTERNAL_H_
+#define COSMOPOLITAN_LIBC_TIME_CLOCKSTONANOS_INTERNAL_H_
+#if !(__ASSEMBLER__ + __LINKER__ + 0)
+COSMOPOLITAN_C_START_
+
+static inline uint64_t ClocksToNanos(uint64_t x, uint64_t y) {
+  // approximation of round(x*.323018) which is usually
+  // the ratio between inva rdtsc ticks and nanoseconds
+  uint128_t difference = x - y;
+  return (difference * 338709) >> 20;
+}
+
+COSMOPOLITAN_C_END_
+#endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */
+#endif /* COSMOPOLITAN_LIBC_TIME_CLOCKSTONANOS_INTERNAL_H_ */