remove unnecessary explicit type conversion (to char) for appendStringInfoChar function calls

Hi,
In the current master code, 3 places we are using appendStringInfoChar
call with explicit type conversion into char. This is not needed as
all other places, we are using direct character to append.

--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -302,7 +302,7 @@ InteractiveBackend(StringInfo inBuf)
*/

/* Add '\0' to make it look the same as message case. */
- appendStringInfoChar(inBuf, (char) '\0');
+ appendStringInfoChar(inBuf, '\0');

Here, I am attaching a small patch to fix these 3 type conversions on head.

--
Thanks and Regards
Mahendra Singh Thalor
EnterpriseDB: http://www.enterprisedb.com