json-lexer: Drop 'buf'

QString supports adding a single char, 'buf' is unneeded.

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>

json-lexer.c

diff --git a/json-lexer.c b/json-lexer.c
index 5cc7e6c..1d9b81f 100644
--- a/json-lexer.c
+++ b/json-lexer.c
@@ -284,8 +284,6 @@
 
 static int json_lexer_feed_char(JSONLexer *lexer, char ch)
 {
-    char buf[2];
-
     lexer->x++;
     if (ch == '\n') {
         lexer->x = 0;
@@ -313,10 +311,7 @@
         break;
     }
 
-    buf[0] = ch;
-    buf[1] = 0;
-
-    qstring_append(lexer->token, buf);
+    qstring_append_chr(lexer->token, ch);
 
     return 0;
 }