Rename globalShareContext to qt_gl_global_share_context

This makes it easier to forward-declare the exported symbol from
other Qt modules without having to include the private headers.

This keeps the old API until dependent submodules are updated.

Change-Id: I08310a684b79f2f612f2ce897a601ff74178bee6
Reviewed-by: Laszlo Agocs <laszlo.agocs@digia.com>

src/gui/kernel/qopenglcontext.cpp

@@ -242,6 +242,27 @@ QHash<QOpenGLContext *, bool> QOpenGLContextPrivate::makeCurrentTracker;
 QMutex QOpenGLContextPrivate::makeCurrentTrackerMutex;
 #endif
 
+/*!
+    \internal
+
+    This function is used by the Qt WebEngine to set up context sharing
+    across multiple windows. Do not use it for any other purpose.
+
+    Please maintain the binary compatibility of these functions.
+*/
+void qt_gl_set_global_share_context(QOpenGLContext *context)
+{
+    global_share_context = context;
+}
+
+/*!
+    \internal
+*/
+QOpenGLContext *qt_gl_global_share_context()
+{
+    return global_share_context;
+}
+
 /*!
     \class QOpenGLContext
     \inmodule QtGui
@@ -336,23 +357,14 @@ QOpenGLContext *QOpenGLContextPrivate::setCurrentContext(QOpenGLContext *context
     return previous;
 }
 
-/*!
-    \internal
-
-    This function is used by the Qt WebEngine to set up context sharing
-    across multiple windows. Do not use it for any other purpose.
-*/
 void QOpenGLContextPrivate::setGlobalShareContext(QOpenGLContext *context)
 {
-    global_share_context = context;
+    qt_gl_set_global_share_context(context);
 }
 
-/*!
-    \internal
-*/
 QOpenGLContext *QOpenGLContextPrivate::globalShareContext()
 {
-    return global_share_context;
+    return qt_gl_global_share_context();
 }
 
 int QOpenGLContextPrivate::maxTextureSize()

src/gui/kernel/qopenglcontext_p.h

@@ -275,6 +275,9 @@ public:
 #endif
 };
 
+Q_GUI_EXPORT void qt_gl_set_global_share_context(QOpenGLContext *context);
+Q_GUI_EXPORT QOpenGLContext *qt_gl_global_share_context();
+
 QT_END_NAMESPACE
 
 #endif // QT_NO_OPENGL

src/widgets/kernel/qwidget.cpp

@@ -11986,7 +11986,7 @@ QOpenGLContext *QWidgetPrivate::shareContext() const
     QWidgetPrivate *that = const_cast<QWidgetPrivate *>(this);
     if (!extra->topextra->shareContext) {
         QOpenGLContext *ctx = new QOpenGLContext;
-        ctx->setShareContext(QOpenGLContextPrivate::globalShareContext());
+        ctx->setShareContext(qt_gl_global_share_context());
         ctx->setFormat(extra->topextra->window->format());
         ctx->create();
         that->extra->topextra->shareContext = ctx;