ruby-mini_portile2: update to 2.8.5.

Upstream changes:
https://github.com/flavorjones/mini_portile/releases/tag/v2.8.5

2.8.5 / 2023-10-22

Added

  * New methods #lib_path and #include_path which point at the installed
    directories under ports. (by @flavorjones)
  * Add config param for CMAKE_BUILD_TYPE, which now defaults to Release.
    (#136 by @Watson1978)

Experimental

Introduce experimental support for MiniPortile#mkmf_config which sets up
MakeMakefile variables to properly link against the recipe. This should
make it easier for C extensions to package third-party libraries.
(by @flavorjones)

  * With no arguments, will set up just $INCFLAGS, $libs, and $LIBPATH.
  * Optionally, if provided a pkg-config file, will use that config to
    more precisely set $INCFLAGS, $libs, $LIBPATH, and $CFLAGS/$CXXFLAGS.
  * Optionally, if provided the name of a static archive, will rewrite
    linker flags to ensure correct linkage.

Note that the behavior may change slightly before official support is
announced. Please comment on #118 if you have feedback.

(tsutsui)