Buildsystem/MSVC: Warning fixes

C4800 'type' : forcing value to bool 'true' or 'false' (performance warning)
C4127 conditional expression is constant

src/server/scripts/Spells/spell_generic.cpp

@@ -3028,7 +3028,7 @@ class spell_gen_replenishment : public SpellScriptLoader
 
             bool Load() override
             {
-                return GetUnitOwner()->GetPower(POWER_MANA);
+                return GetUnitOwner()->getPowerType() == POWER_MANA;
             }
 
             void CalculateAmount(AuraEffect const* /*aurEff*/, int32& amount, bool& /*canBeRecalculated*/)