configure.in: default LINK_SO

* configure.in: should not strip newline at the beginning for the
  default link command.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@40582 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

configure.in

@@ -899,8 +899,8 @@ main()
 		AC_CHECK_PROGS(codesign, codesign)
 		if test -n "$codesign"; then
 		    POSTLINK="test -z '\$(RUBY_CODESIGN)' || $codesign -s '\$(RUBY_CODESIGN)' -f \$@"
-		    LINK_SO="$LINK_SO${LINK_SO:+
-}\$(POSTLINK)"
+		    LINK_SO="$LINK_SO
+\$(POSTLINK)"
 		fi
 		AC_CHECK_HEADERS(crt_externs.h, [], [], [
 		    #include <crt_externs.h>