PyImport_AppendInittab() took a char * as a first argument even though that
string was stored beyond the life of the call. Changed the signature to be
const char * to help make this point.

Closes issue #1419652.
diff --git a/Python/import.c b/Python/import.c
index 98b8dce..b39cb18 100644
--- a/Python/import.c
+++ b/Python/import.c
@@ -3376,7 +3376,7 @@
 /* Shorthand to add a single entry given a name and a function */
 
 int
-PyImport_AppendInittab(char *name, void (*initfunc)(void))
+PyImport_AppendInittab(const char *name, void (*initfunc)(void))
 {
 	struct _inittab newtab[2];