tt: Fixup tt build for new includes locations

Some files were trying to access the global includes directy in the
build area with things like #include <api/c/tt_c.h>, which is now
wrong.  Se we fix all of those up.  tt_c.h and tttk.h are now global,
so we no longer need to root around various build dirs to find them.

TT builds again.

cde/lib/tt/bin/ttauth/process.c

@@ -61,7 +61,7 @@ extern int errno;
 #endif
 #include "ttauth.h"
 #include "api/c/api_auth.h"
-#include "api/c/tt_c.h"
+#include "Tt/tt_c.h"
 
 #include <signal.h>
 

cde/lib/tt/bin/ttauth/ttauth.c

@@ -50,7 +50,7 @@ in this Software without prior written authorization from The Open Group.
  */
 
 #include "ttauth.h"
-#include "api/c/tt_c.h"
+#include "Tt/tt_c.h"
 
 
 /*