patch 8.2.3985: error messages are spread out

Problem:    Error messages are spread out.
Solution:   Move more error messages to errors.h.
diff --git a/src/os_win32.c b/src/os_win32.c
index e4ebc0c..fb1b29d 100644
--- a/src/os_win32.c
+++ b/src/os_win32.c
@@ -4954,7 +4954,7 @@
 # ifdef VIMDLL
 		if (gui.in_use)
 # endif
-		    emsg(_("E371: Command not found"));
+		    emsg(_(e_command_not_found));
 #endif
 	    }