Remove stray debug output

This was actually causing test failures in qtdeclarative
and blocking the CI there.

Change-Id: I4538342f16b6468ad60b283c19948863b20ad5d4
Reviewed-by: Gunnar Sletta <gunnar.sletta@digia.com>

src/plugins/platforms/cocoa/qcocoaglcontext.mm

@@ -242,7 +242,6 @@ void QCocoaGLContext::updateSurfaceFormat()
     // attribute to check explicitly for this so we use our best guess for alpha.
     int alphaSize = -1;
     [pixelFormat getValues:&alphaSize forAttribute:NSOpenGLPFAAlphaSize forVirtualScreen:0];
-    qDebug() << "alphaSize =" << alphaSize;
     if (alphaSize > 0 && requestedFormat.alphaBufferSize() > 0)
         m_format.setAlphaBufferSize(alphaSize);