remove unnecessary casting between XGL_CHAR/char

Many of the changed lines are generated.  That should be fixed at some point.
diff --git a/demos/xglinfo.c b/demos/xglinfo.c
index 84ae453..4dec489 100644
--- a/demos/xglinfo.c
+++ b/demos/xglinfo.c
@@ -291,7 +291,7 @@
     XGL_UINT i;
 
     static const XGL_CHAR *known_extensions[] = {
-        (const XGL_CHAR *) "XGL_WSI_X11",
+        "XGL_WSI_X11",
     };
 
     for (i = 0; i < ARRAY_SIZE(known_extensions); i++) {
@@ -605,9 +605,9 @@
     static const XGL_APPLICATION_INFO app_info = {
         .sType = XGL_STRUCTURE_TYPE_APPLICATION_INFO,
         .pNext = NULL,
-        .pAppName = (const XGL_CHAR *) "xglinfo",
+        .pAppName = "xglinfo",
         .appVersion = 1,
-        .pEngineName = (const XGL_CHAR *) "xglinfo",
+        .pEngineName = "xglinfo",
         .engineVersion = 1,
         .apiVersion = XGL_MAKE_VERSION(0, 22, 0),
     };