Delegated renderer: Share context support for QNX

Add code to extract the EGL context on QNX for use as the share context
in the Chromium GPU process/thread. Very similar to the other
platforms.

Change-Id: I54fba69283e984a392c11922da2483ce921ea594
Reviewed-by: Jocelyn Turcotte <jocelyn.turcotte@digia.com>

lib/content_browser_client_qt.cpp

@@ -222,6 +222,8 @@ public:
                 m_handle = pni->nativeResourceForContext(QByteArrayLiteral("glxcontext"), qtContext);
         } else if (platform == QStringLiteral("Cocoa"))
             m_handle = pni->nativeResourceForContext(QByteArrayLiteral("cglcontextobj"), qtContext);
+        else if (platform == QStringLiteral("qnx"))
+            m_handle = pni->nativeResourceForContext(QByteArrayLiteral("eglcontext"), qtContext);
         else
             // Add missing platforms once they work.
             Q_UNREACHABLE();