A close-parenthesis in a guru.dat response string would throw-off the parser

After a negative-match of a Guru expression, we were searching for the next
'(' anywhere in the subsequent chars of the file rather than just the next
line that started with an open-parenthesis character.

This bug was the secondary cause of the buffer-overflow crash addresseed in
commit 62e2280e which was triggered by my recent updates to the guru.dat.

src/sbbs3/chat.cpp

@@ -1519,7 +1519,7 @@ void sbbs_t::guruchat(char* line, char* gurubuf, int gurunum, char* last_answer)
 		if(*ptr=='(') {
 			ptr++;
 			if(!guruexp(&ptr,cstr)) {
-				while(*ptr && *ptr!='(' && ptr<gurubuf+len)
+				while(*ptr && !(*ptr == '(' && *(ptr-1) == '\n') && ptr<gurubuf+len)
 					ptr++;
 				continue;
 			}