fix incorrect type caused issue on 64bit powerpc

Signed-off-by: Insop Song <insop.song@gainspeed.com>
diff --git a/linenoise.c b/linenoise.c
index c4e3118..06716fa 100644
--- a/linenoise.c
+++ b/linenoise.c
@@ -461,7 +461,7 @@
 /* Insert the character 'c' at cursor current position.
  *
  * On error writing to the terminal -1 is returned, otherwise 0. */
-int linenoiseEditInsert(struct linenoiseState *l, int c) {
+int linenoiseEditInsert(struct linenoiseState *l, char c) {
     if (l->len < l->buflen) {
         if (l->len == l->pos) {
             l->buf[l->pos] = c;