Properly check for extensions in Framebuffer GL test.

src/Magnum/Test/FramebufferGLTest.cpp

@@ -633,6 +633,11 @@ void FramebufferGLTest::attachCubeMapTextureArray() {
 #endif
 
 void FramebufferGLTest::detach() {
+    #ifndef MAGNUM_TARGET_GLES
+    if(!Context::current()->isExtensionSupported<Extensions::GL::ARB::framebuffer_object>())
+        CORRADE_SKIP(Extensions::GL::ARB::framebuffer_object::string() + std::string(" is not available."));
+    #endif
+
     Framebuffer framebuffer({{}, Vector2i(128)});
     framebuffer.detach(Framebuffer::ColorAttachment(0))
                .detach(Framebuffer::BufferAttachment::Depth)
@@ -691,6 +696,11 @@ void FramebufferGLTest::multipleColorOutputs() {
 }
 
 void FramebufferGLTest::clear() {
+    #ifndef MAGNUM_TARGET_GLES
+    if(!Context::current()->isExtensionSupported<Extensions::GL::ARB::framebuffer_object>())
+        CORRADE_SKIP(Extensions::GL::ARB::framebuffer_object::string() + std::string(" is not available."));
+    #endif
+
     Renderbuffer color;
     #ifndef MAGNUM_TARGET_GLES2
     color.setStorage(RenderbufferFormat::RGBA8, Vector2i(128));