"Gnomish Shrink Ray" fix with roll

The author assumed that the roll variable would be assigned with a
random value, and then this value would be compared with 3. However, the
priority of the comparison operation is higher than of the assignment
operation (see the table "Operation priorities in C/C++", so the random
number will be compared with 3 first, and then the result of the
comparison (0 or 1) will be written to the roll variable.

Close cmangos/mangos-classic#258

(based on cmangos/mangos-wotlk@c7c1fc302)

Signed-off-by: Xfurry <xfurry.cmangos@outlook.com>

src/game/Spells/SpellEffects.cpp

@@ -891,8 +891,9 @@ void Spell::EffectDummy(SpellEffectEntry const* effect)
                 {
                     if (unitTarget && m_CastItem)
                     {
+                        uint32 roll = urand(0, 99);
                         // These rates are hella random; someone feel free to correct them
-                        if (uint32 roll = urand(0, 99) < 3)                   // Whole party will grow
+                        if (roll < 3)                                         // Whole party will grow
                             m_caster->CastSpell(m_caster, 13004, TRIGGERED_OLD_TRIGGERED);
                         else if (roll < 6)                                    // Whole party will shrink
                             m_caster->CastSpell(m_caster, 13010, TRIGGERED_OLD_TRIGGERED);