Fix a warning from gcc by adding a missed const qualifier.
diff --git a/Python/dynload_shlib.c b/Python/dynload_shlib.c
index 960e5c0..f12a93c 100644
--- a/Python/dynload_shlib.c
+++ b/Python/dynload_shlib.c
@@ -130,7 +130,7 @@
 	handle = dlopen(pathname, dlopenflags);
 
 	if (handle == NULL) {
-		char *error = dlerror();
+		const char *error = dlerror();
 		if (error == NULL)
 			error = "unknown dlopen() error";
 		PyErr_SetString(PyExc_ImportError, error);