fire launch: Avoid "may be used uninitialized" warnings

launch_missile() initializes @n to the target ship number only when
the target is a ship.  It also uses it only then, to re-get the ship.
Clang is cool with this, but GCC gets confused and warns "‘n’ may be
used uninitialized".

Use target_ship.shp_uid instead of @n to avoid the warning.

Similar issue in c_fire(): use vship.shp_uid instead of for @vhsipno.

Signed-off-by: Markus Armbruster <armbru@pond.sub.org>

src/lib/commands/laun.c

@@ -263,7 +263,8 @@ launch_missile(struct plnstr *pp)
 		       target_ship.shp_x, target_ship.shp_y,
 		       target_ship.shp_own, &sublaunch) < 0)
 	    return RET_OK;
-	getship(n, &target_ship);
+	/* @target_ship may have expended shells defending */
+	getship(target_ship.shp_uid, &target_ship);
 	if (!msl_hit(pp, shp_hardtarget(&target_ship), EF_SHIP,
 		     N_SHP_MISS, N_SHP_SMISS, sublaunch,
 		     target_ship.shp_own)) {

src/lib/commands/mfir.c

@@ -393,7 +393,7 @@ c_fire(void)
 	    putsect(&vsect);
 	    break;
 	default:
-	    getship(vshipno, &vship);
+	    getship(vship.shp_uid, &vship);
 	    shipdamage(&vship, dam);
 	    if (vship.shp_effic < SHIP_MINEFF)
 		pr("%s sunk!\n", prsub(&vship));