Resolve warnings on Windows

Appease the compiler by resolving some of the reported warnings,
including:

- Control paths that don't return.

- Potentially uninitialized variables.

- Unused local variables.

- Unreachable code.

- Type safety.

- Synchronize declarations with definitions for functions.

lib/wind/errorlist.c

@@ -49,7 +49,7 @@ error_entry_cmp(const void *a, const void *b)
 }
 
 int
-_wind_stringprep_error(uint32_t cp, wind_profile_flags flags)
+_wind_stringprep_error(const uint32_t cp, wind_profile_flags flags)
 {
     struct error_entry ee = {cp};
     const struct error_entry *s;