Suppress 'uninitialized variable' warning emitted by some (not all)

versions of gcc.  The code is correct AFAICS, but it requires slightly
more analysis than usual to see that the variable can't be used uninitialized.

contrib/tsearch2/ispell/spell.c

@@ -791,7 +791,7 @@ CopyVar(SplitVar *s, int makedup) {
 static SplitVar*
 SplitToVariants( IspellDict * Conf, SPNode *snode, SplitVar * orig, char *word, int wordlen, int startpos, int minpos ) {
 	SplitVar *var=NULL;
-	SPNodeData *StopLow, *StopHigh, *StopMiddle;
+	SPNodeData *StopLow, *StopHigh, *StopMiddle = NULL;
 	SPNode *node = (snode) ? snode : Conf->Dictionary;
 	int level=(snode) ? minpos : startpos; /* recursive minpos==level*/
 	int lenaff;