Change GetProcAddr  function signature to use XGL types.

Fix bug in GPA for basic_plugin.c .
diff --git a/loader/loader.c b/loader/loader.c
index b561873..0427600 100644
--- a/loader/loader.c
+++ b/loader/loader.c
@@ -739,7 +739,7 @@
 
 #endif
 
-LOADER_EXPORT void * XGLAPI xglGetProcAddr(XGL_PHYSICAL_GPU gpu, const XGL_CHAR * pName) {
+LOADER_EXPORT XGL_VOID * XGLAPI xglGetProcAddr(XGL_PHYSICAL_GPU gpu, const XGL_CHAR * pName) {
 
     if (gpu == NULL)
         return NULL;