configure.in: use BASERUBY

* configure.in (BOOTSTRAPRUBY): use BASERUBY if available.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@51749 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

configure.in

@@ -3435,6 +3435,7 @@ else
   RUNRUBY='$(RUNRUBY_COMMAND) --'
   XRUBY='$(RUNRUBY)'
   BOOTSTRAPRUBY='$(MINIRUBY)'
+  test x"${HAVE_BASERUBY}" = xyes && BOOTSTRAPRUBY='$(BASERUBY)'
   TEST_RUNNABLE=yes
   CROSS_COMPILING=no
 fi