rhi: Add a way to query the parent QRhi from a resource

Quick3D introduces the need to verify the QRhi when only a
QRhiTexture (pulled out from a QSGTexture) is available. To
enable this, there needs to be a way to retrieve the QRhi
from the QRhiTexture.

Change-Id: I00777f08b030a7de742169beb0b99ca6282d51a6
Reviewed-by: Christian Strømme <christian.stromme@qt.io>

src/gui/rhi/qrhi.cpp

@@ -2211,6 +2211,14 @@ quint64 QRhiResource::globalResourceId() const
     return m_id;
 }
 
+/*!
+    \return the QRhi that created this resource.
+ */
+QRhi *QRhiResource::rhi() const
+{
+    return m_rhi->q;
+}
+
 /*!
     \class QRhiBuffer
     \internal

src/gui/rhi/qrhi_p.h

@@ -30,6 +30,7 @@
 QT_BEGIN_NAMESPACE
 
 class QWindow;
+class QRhi;
 class QRhiImplementation;
 class QRhiBuffer;
 class QRhiRenderBuffer;
@@ -684,6 +685,8 @@ public:
 
     quint64 globalResourceId() const;
 
+    QRhi *rhi() const;
+
 protected:
     QRhiResource(QRhiImplementation *rhi);
     Q_DISABLE_COPY(QRhiResource)