* include/sys/cygwin.h (CW_SETERRNO): Define.

* external.cc (CW_SETERRNO): Implement.
* include/cygwin/version.h: Bump CYGWIN_VERSION_API_MINOR to 192 to reflect the
above change.
* path.cc (path_prefix_p): Treat X: as equivalent to x:.
* mkglobals_h: Remove unneeded #define.
* spawn.cc (spawn_guts): Avoid overly wordy initialization to zero.

winsup/cygwin/spawn.cc

@@ -310,8 +310,7 @@ spawn_guts (const char *prog_arg, const char *const *argv,
   cygheap_exec_info *moreinfo;
 
   bool null_app_name = false;
-  STARTUPINFOW si = {0, NULL, NULL, NULL, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, NULL,
-		     NULL, NULL, NULL};
+  STARTUPINFOW si = {};
   int looped = 0;
   HANDLE orig_wr_proc_pipe = NULL;