use <<- instead of <<~ for older baseruby

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@62386 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

tool/ruby_vm/views/_mjit_compile_insn_body.erb

@@ -23,7 +23,7 @@
 %     # For `leave`. We can't proceed next ISeq in the same JIT function.
 %     expr.gsub!(/^(?<indent>\s*)RESTORE_REGS\(\);\n/) do
 %       indent = Regexp.last_match[:indent]
-%       <<~RESTORE_REGS
+%       <<-RESTORE_REGS.gsub(/^ +/, '')
 %         #if OPT_CALL_THREADED_CODE
 %         #{indent}rb_ec_thread_ptr(ec)->retval = val;
 %         #{indent}return 0;