patch 8.2.3749: error messages are everywhere

Problem:    Error messages are everywhere.
Solution:   Move more error messages to errors.h and adjust the names.
diff --git a/src/memfile.c b/src/memfile.c
index a414d9e..fbffdbe 100644
--- a/src/memfile.c
+++ b/src/memfile.c
@@ -242,7 +242,7 @@
     if (mfp->mf_fd >= 0)
     {
 	if (close(mfp->mf_fd) < 0)
-	    emsg(_(e_swapclose));
+	    emsg(_(e_close_error_on_swap_file));
     }
     if (del_file && mfp->mf_fname != NULL)
 	mch_remove(mfp->mf_fname);
@@ -288,7 +288,7 @@
     }
 
     if (close(mfp->mf_fd) < 0)			// close the file
-	emsg(_(e_swapclose));
+	emsg(_(e_close_error_on_swap_file));
     mfp->mf_fd = -1;
 
     if (mfp->mf_fname != NULL)