Fixed compiler warnings

Remove compiler warnings in sphinx, item_sum.cc and opt_split.cc

sql/item_sum.cc

@@ -2414,7 +2414,7 @@ Item *Item_sum_min::copy_or_same(THD* thd)
 
 bool Item_sum_min::add()
 {
-  Item *tmp_item;
+  Item *UNINIT_VAR(tmp_item);
   DBUG_ENTER("Item_sum_min::add");
   DBUG_PRINT("enter", ("this: %p", this));
 

sql/opt_split.cc

@@ -866,8 +866,8 @@ SplM_plan_info * JOIN_TAB::choose_best_splitting(double record_count,
   TABLE *best_table= 0;
   double best_rec_per_key= DBL_MAX;
   SplM_plan_info *spl_plan= 0;
-  uint best_key;
-  uint best_key_parts;
+  uint best_key= 0;
+  uint best_key_parts= 0;
 
   /*
     Check whether there are keys that can be used to join T employing splitting

storage/sphinx/snippets_udf.cc

@@ -177,10 +177,10 @@ enum
 	SEARCHD_WARNING	= 3		///< general success, warning message and command-specific reply follow
 };
 
-#define SPHINXSE_DEFAULT_SCHEME		"sphinx"
-#define SPHINXSE_DEFAULT_HOST		"127.0.0.1"
+#define SPHINXSE_DEFAULT_SCHEME		(char*) "sphinx"
+#define SPHINXSE_DEFAULT_HOST		(char*) "127.0.0.1"
 #define SPHINXSE_DEFAULT_PORT		9312
-#define SPHINXSE_DEFAULT_INDEX		"*"
+#define SPHINXSE_DEFAULT_INDEX		(char*) "*"
 
 class CSphBuffer
 {
@@ -446,7 +446,7 @@ int CSphUrl::Connect()
 	uint uServerVersion;
 	uint uClientVersion = htonl ( SPHINX_SEARCHD_PROTO );
 	int iSocket = -1;
-	char * pError = NULL;
+	const char * pError = NULL;
 	do
 	{
 		iSocket = (int)socket ( iDomain, SOCK_STREAM, 0 );