Make improvements

- Add GetCpuCount() API to redbean
- Add unix.gmtime() API to redbean
- Add unix.readlink() API to redbean
- Add unix.localtime() API to redbean
- Perfect the new redbean UNIX module APIs
- Integrate with Linux clock_gettime() vDSO
- Run Lua garbage collector when malloc() fails
- Fix another regression quirk with linenoise repl
- Fix GetProgramExecutableName() for systemwide installs
- Fix a build flake with test/libc/mem/test.mk SRCS list

tool/net/demo/unix-raise.lua

@@ -0,0 +1,11 @@
+#!/home/jart/bin/redbean -i
+assert(unix.sigaction(unix.SIGUSR1, function(sig)
+   gotsigusr1 = true
+end))
+gotsigusr1 = false
+assert(unix.raise(unix.SIGUSR1))
+if gotsigusr1 then
+   print('hooray the signal was delivered')
+else
+   print('oh no some other signal was handled')
+end