Add PicoRuby 3.4.2 with new build function for r2p2

This commit adds PicoRuby 3.4.2 and introduces a new build function to accommodate changes in the build artifacts.

Version numbering context:
PicoRuby's version numbers are aligned with mruby's VM code specification compatibility.
Version 3.4 indicates compatibility with mruby 3.4 VM code format, or RITE0300.
Version 3.4.2 indicates minor bug fix in PicoRuby.

Build artifact changes:
Starting from version 3.4.2, PicoRuby has replaced the irb executable with r2p2 (POSIX version of PicoRuby shell system including IRB).
The new build produces three executables:
- picoruby: main Ruby interpreter
- picorbc: Ruby bytecode compiler
- r2p2: interactive REPL (replaces picoirb)

Implementation:
- Added build_package_picoruby_r2p2() function for version 3.4.2+
- Existing build_package_picoruby() remains for version 3.0.0
- The new function creates only the 'ruby' symlink, omitting 'irb'
- Added picoruby-3.4.2 definition file

The split in build functions allows proper support for both the legacy
3.0.0 release with irb and newer releases with r2p2.

Author: hasumikin

bin/ruby-build

@@ -888,6 +888,13 @@ build_package_picoruby() {
   ln -fs picoirb "$PREFIX_PATH/bin/irb"
 }
 
+build_package_picoruby_r2p2() {
+  capture_command ./minirake
+  mkdir -p "$PREFIX_PATH"
+  cp -fR build/host/* include "$PREFIX_PATH"
+  ln -fs picoruby "$PREFIX_PATH/bin/ruby"
+}
+
 build_package_jruby() {
   build_package_copy
   # shellcheck disable=SC2164

share/ruby-build/picoruby-3.4.2

@@ -0,0 +1 @@
+install_package "picoruby-3.4.2" "https://github.com/picoruby/picoruby/releases/download/3.4.2/picoruby-3.4.2.tar.gz#75a7dded2b2dff443a80e3bb8075ccf2fe7b77282f8a8a69689fc700b51d61f3" picoruby_r2p2