do not discard constness in interp_set_entry value argument

Signed-off-by: Alex Riesen <raa.lkml@gmail.com>
Signed-off-by: Junio C Hamano <junkio@cox.net>

interpolate.c

@@ -8,10 +8,10 @@
 #include "interpolate.h"
 
 
-void interp_set_entry(struct interp *table, int slot, char *value)
+void interp_set_entry(struct interp *table, int slot, const char *value)
 {
 	char *oldval = table[slot].value;
-	char *newval = value;
+	char *newval = NULL;
 
 	if (oldval)
 		free(oldval);

interpolate.h

@@ -16,7 +16,7 @@ struct interp {
 	char *value;
 };
 
-extern void interp_set_entry(struct interp *table, int slot, char *value);
+extern void interp_set_entry(struct interp *table, int slot, const char *value);
 extern void interp_clear_table(struct interp *table, int ninterps);
 
 extern int interpolate(char *result, int reslen,