extensions: begin changes for extension support

This patch starts restructuring the various components
(loader, driver, layers, etc.) to support global and
device extensions. Require GetProcAddr to access the
extension functions and related support.
diff --git a/icd/intel/sampler.c b/icd/intel/sampler.c
index 75dbd60..ff25590 100644
--- a/icd/intel/sampler.c
+++ b/icd/intel/sampler.c
@@ -368,7 +368,7 @@
     struct intel_sampler *sampler;
 
     sampler = (struct intel_sampler *) intel_base_create(&dev->base.handle,
-            sizeof(*sampler), dev->base.dbg, VK_DBG_OBJECT_SAMPLER, info, 0);
+            sizeof(*sampler), dev->base.dbg, VK_OBJECT_TYPE_SAMPLER, info, 0);
     if (!sampler)
         return VK_ERROR_OUT_OF_HOST_MEMORY;