add new Literal API for pure literal expressions:

Design compile time api hs_compile_lit() and hs_compile_lit_multi()
to handle pure literal pattern sets. Corresponding option --literal-on
is added for hyperscan testing suites. Extended parameters and part of
flags are not supported for this api.

src/rose/rose_internal.h

@@ -328,6 +328,7 @@ struct RoseBoundaryReports {
  *  nfas). Rose nfa info table can distinguish the cases.
  */
 struct RoseEngine {
+    u8  pureLiteral; /* Indicator of pure literal API */
     u8  noFloatingRoots; /* only need to run the anchored table if something
                           * matched in the anchored table */
     u8  requiresEodCheck; /* stuff happens at eod time */