Remove wrong #ifdef in Option_String()

This fixes the following error when compiling without zlib support:

  irc.c: In function ‘Option_String’:
  irc.c:487: error: ‘options’ undeclared (first use in this function)

Reported by "der_baer" on #ngircd.

src/ngircd/irc.c

@@ -478,9 +478,7 @@ Option_String(UNUSED CONN_ID Idx)
 #endif
 {
 	static char option_txt[8];
-#ifdef ZLIB
 	UINT16 options;
-#endif
 
 	assert(Idx != NONE);