Avoid comparing unintialised variable if BREEZE_HAVE_KSTYLE is not set

if BREEZE_HAVE_KSTYLE is not set CE_CapacityBar remains uninitialised
(random value). It should therefore not be used in any comparisons.

For KDE4, BREEZE_HAVE_KSTYLE will always be false regardless so that
behaviour remains the same

kstyle/breezestyle.cpp

@@ -807,7 +807,7 @@ namespace Breeze
 
         StyleControl fcn( nullptr );
 
-        #if !BREEZE_USE_KDE4
+        #if BREEZE_HAVE_KSTYLE
         if( element == CE_CapacityBar )
         {
             fcn = &Style::drawProgressBarControl;