xcb: Rename main.cpp to xcbmain.cpp

Files with same base name cause extra trouble for debuggers.
It can be avoided here.

Change-Id: I1b7a6f28ac41bacbfd2603feb8b786c31d3769e3
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Shawn Rutledge <shawn.rutledge@digia.com>

src/plugins/platforms/xcb/qxcbmain.cpp

@@ -62,4 +62,4 @@ QPlatformIntegration* QXcbIntegrationPlugin::create(const QString& system, const
 
 QT_END_NAMESPACE
 
-#include "main.moc"
+#include "qxcbmain.moc"

src/plugins/platforms/xcb/xcb-plugin.pro

@@ -17,7 +17,7 @@ SOURCES = \
         qxcbwindow.cpp \
         qxcbbackingstore.cpp \
         qxcbwmsupport.cpp \
-        main.cpp \
+        qxcbmain.cpp \
         qxcbnativeinterface.cpp \
         qxcbcursor.cpp \
         qxcbimage.cpp \