Base profile: Select Ruby 2.4 as our LTS Ruby interpreter

profiles/base/make.defaults

@@ -40,6 +40,9 @@ PROFILE_ONLY_VARIABLES="ARCH ELIBC IUSE_IMPLICIT KERNEL USERLAND USE_EXPAND_IMPL
 PYTHON_TARGETS="python3_5"
 PYTHON_SINGLE_TARGET="python3_5"
 
+# Ruby 2.4 will be supported until at least December 2019.
+RUBY_TARGETS="ruby24"
+
 # These USE will be forced onto every system running Adélie.  DO NOT MODIFY THIS LIGHTLY!
 USE="cxx icu -introspection ipv6 modules ssl unicode xattr"