Ruby 2.6 Removal

Per our standard Ruby support policy, I am planning to remove Ruby 2.6
from the ports tree, as it will be completely unsupported before the
release of OpenBSD 7.1. Nothing currently depends on it, so
this should cause no problems.

Here's the diff for ruby.port.mk. I also have diffs prepared for
ruby-module.5 and quirks.

Thanks,
Jeremy

Index: ruby.port.mk
===================================================================
RCS file: /cvs/ports/lang/ruby/ruby.port.mk,v
retrieving revision 1.104
diff -u -p -r1.104 ruby.port.mk
--- ruby.port.mk 2 Sep 2021 14:59:44 -0000 1.104
+++ ruby.port.mk 24 Sep 2021 15:20:20 -0000
@@ -24,7 +24,7 @@ MODRUBY_HANDLE_FLAVORS ?= No
# If ruby.pork.mk should handle FLAVORs, define a separate FLAVOR
# for each ruby interpreter
. if !defined(FLAVORS)
-FLAVORS= ruby26 ruby27 ruby30
+FLAVORS= ruby27 ruby30
. if !${CONFIGURE_STYLE:L:Mext}
FLAVORS+= jruby
. endif
@@ -52,11 +52,10 @@ FLAVOR = ruby30

# Check for conflicting FLAVORs and set MODRUBY_REV appropriately based
# on the FLAVOR.
-. for i in ruby26 ruby27 ruby30 jruby
+. for i in ruby27 ruby30 jruby
. if ${FLAVOR:M$i}
MODRUBY_REV = ${i:C/ruby([0-9])/\1./}
-. if ${FLAVOR:N$i:Mruby26} || \
- ${FLAVOR:N$i:Mruby27} || \
+. if ${FLAVOR:N$i:Mruby27} || \
${FLAVOR:N$i:Mruby30} || \
${FLAVOR:N$i:Mjruby}
ERRORS += "Fatal: Conflicting flavors used: ${FLAVOR}"