re2c: upgrade 4.1 -> 4.2

re2c: upgrade 4.1 -> 4.2

Changelog:
============
- Added Swift backend
- Added options:
   "--lang swift"
   "--computed-gotos-relative"
- Added configurations:
   "re2c:cgoto:relative", "re2c:computed-gotos:relative"
   "re2c:yyfn:throw"
- Added syntax file code templates:
   "code:cgoto"
   "code:cgoto_data"
   "code:yytarget_filter"
   "code:type_yyctable"
- Added syntax file conditionals:
   ".cgoto.relative"
   ".yyfn.throw"

- Added some C++ benchmarks without submatch extraction.

Signed-off-by: Wang Mingyu <wangmy@fujitsu.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>