Don't try to load opengl extensions or functions without QLibrary

Change-Id: If77ca6e04c83d94fd3063b68963b1bcd90980d99
Reviewed-by: Laszlo Agocs <laszlo.agocs@theqtcompany.com>

src/gui/opengl/qopenglextensions_p.h

@@ -78,8 +78,9 @@ public:
 private:
     bool init();
     QFunctionPointer resolve(const char *name);
-
+#ifndef QT_NO_LIBRARY
     QLibrary m_gl;
+#endif
 };
 
 class Q_GUI_EXPORT QOpenGLExtensions : public QOpenGLFunctions

src/gui/opengl/qopenglfunctions.cpp

@@ -3208,7 +3208,9 @@ Q_GLOBAL_STATIC(QOpenGLES3Helper, qgles3Helper)
 
 bool QOpenGLES3Helper::init()
 {
-#ifndef Q_OS_IOS
+#ifdef QT_NO_LIBRARY
+    return false;
+#elif !defined(Q_OS_IOS)
 # ifdef Q_OS_WIN
 #  ifndef QT_DEBUG
     m_gl.setFileName(QStringLiteral("libGLESv2"));
@@ -3228,8 +3230,11 @@ QFunctionPointer QOpenGLES3Helper::resolve(const char *name)
 {
 #ifdef Q_OS_IOS
     return QFunctionPointer(dlsym(RTLD_DEFAULT, name));
-#else
+#elif !defined(QT_NO_LIBRARY)
     return m_gl.resolve(name);
+#else
+    Q_UNUSED(name);
+    return 0;
 #endif
 }