Improve signal handling and math

- Polyfill ucontext_t on FreeBSD/OpenBSD/NetBSD
- Add tests confirming signals can edit CPU state
- Work towards supporting ZIP filesystem on bare metal
- Add more tinymath unit tests for POSIX conformance
- Add X87 and SSE status flags to crash report
- Fix some bugs in blinkenlights
- Fix llvm build breakage

libc/calls/struct/siginfo.h

@@ -49,7 +49,7 @@ struct siginfo {
     };
     char __ignoreme[128 - 2 * sizeof(int32_t) - sizeof(int64_t)];
   };
-} forcealign(8);
+};
 
 typedef struct siginfo siginfo_t;