Check configs before mutable_render_buffer negative test
Check configs before mutable_render_buffer negative test

Some implementations don't expose any configs without support for
mutable render buffer. Don't test those.

Bug 27129258

Change-Id: I5186630ac81abc31002881c092d9ca50607eb1c4

googlestadia/VK-GL-CTS,KhronosGroup/Vulkan-CTS,chadversary/deqp,KhronosGroup/VK-GL-CTS,googlestadia/VK-GL-CTS,KhronosGroup/VK-GL-CTS,googlestadia/VK-GL-CTS,KhronosGroup/Vulkan-CTS,googlestadia/VK-GL-CTS,KhronosGroup/VK-GL-CTS,chadversary/deqp,KhronosGroup/Vulkan-CTS,chadversary/deqp,googlestadia/VK-GL-CTS,chadversary/deqp,googlestadia/VK-GL-CTS,KhronosGroup/Vulkan-CTS,KhronosGroup/VK-GL-CTS,KhronosGroup/Vulkan-CTS,chadversary/deqp,KhronosGroup/VK-GL-CTS,chadversary/deqp,KhronosGroup/Vulkan-CTS,KhronosGroup/VK-GL-CTS