patch 8.2.3967: error messages are spread out

Problem:    Error messages are spread out.
Solution:   Move more errors to errors.h.
diff --git a/src/if_perl.xs b/src/if_perl.xs
index 3d683bd..37b9cb2 100644
--- a/src/if_perl.xs
+++ b/src/if_perl.xs
@@ -773,7 +773,7 @@
 	    close_dll(hPerlLib);
 	    hPerlLib = NULL;
 	    if (verbose)
-		semsg((const char *)_(e_loadfunc), perl_funcname_table[i].name);
+		semsg((const char *)_(e_could_not_load_library_function_str), perl_funcname_table[i].name);
 	    return FAIL;
 	}
     }