icd: rename and prefix shader_il.h

Rename shader_il.h to icd-bil.h, and make it more C compatible.  Prefix
everything with icd_.
diff --git a/icd/intel/intel.h b/icd/intel/intel.h
index 87b4938..91a8137 100644
--- a/icd/intel/intel.h
+++ b/icd/intel/intel.h
@@ -35,6 +35,7 @@
 #include <xglDbg.h>
 
 #include "icd.h"
+#include "icd-bil.h"
 #include "icd-format.h"
 #include "icd-utils.h"