Removed all instances of crash_prog()

crash_prog was introduced to force-crash a userspace program
since _exit may not yet be implemented. However, the new versions
of OS161 already have the exact same logic as crash_prog in stdlib/exit.

userland/lib/libc/unix/err.c

@@ -140,7 +140,6 @@ verr(int exitcode, const char *fmt, va_list ap)
 	__printerr(1, fmt, ap);
 	exit(exitcode);
 	// exit() didn't work.
-	crash_prog();
 }
 
 /* errx/verrx: don't use errno, but do then exit */
@@ -150,7 +149,6 @@ verrx(int exitcode, const char *fmt, va_list ap)
 	__printerr(0, fmt, ap);
 	exit(exitcode);
 	// exit() didn't work.
-	crash_prog();
 }
 
 /*
@@ -193,12 +191,3 @@ errx(int exitcode, const char *fmt, ...)
 	verrx(exitcode, fmt, ap);
 	va_end(ap);
 }
-
-void
-crash_prog(void)
-{
-	// Guru: Since exit() may not yet be implemented, just trigger a
-	// failure so things don't fall through to a success print
-	nprintf("Accessing invalid memory location to trigger failure\n");
-	tprintf("%d", *((int *) 0xd34db33f));
-}