Avoid implicit conversions, which are now flagged by gcc6

| api/qcoloroutput_p.h:74:60: error: shift expression '(1048575 << 20)' overflows [-fpermissive]
| api/qcoloroutput_p.h:74:63: error: enumerator value for 'BackgroundMask' is not an integer constant
|              BackgroundMask  = ((1 << BackgroundShift) - 1) << BackgroundShift


Upstream-Status: Inappropriate [Frozen upstream]
Signed-off-by: Khem Raj <raj.khem@gmail.com>

diff -up qt-everywhere-opensource-src-4.8.7/src/xmlpatterns/api/qcoloroutput_p.h.than qt-everywhere-opensource-src-4.8.7/src/xmlpatterns/api/qcoloroutput_p.h
--- qt-everywhere-opensource-src-4.8.7/src/xmlpatterns/api/qcoloroutput_p.h.than    2016-02-03 11:43:04.567757448 +0100
+++ qt-everywhere-opensource-src-4.8.7/src/xmlpatterns/api/qcoloroutput_p.h 2016-02-04 13:12:26.394350271 +0100
@@ -70,8 +70,8 @@ namespace QPatternist
             ForegroundShift = 10,
             BackgroundShift = 20,
             SpecialShift    = 20,
-            ForegroundMask  = ((1 << ForegroundShift) - 1) << ForegroundShift,
-            BackgroundMask  = ((1 << BackgroundShift) - 1) << BackgroundShift
+            ForegroundMask  = 0x1f << ForegroundShift,
+            BackgroundMask  = 0x7 << BackgroundShift
         };
 
     public: