time on OSX does not support -f

[deinst]

I'm pretty sure that this is not worth the trouble that it would take to fix, but OSX does not understand time -f "%e" thereby causing make check to fail.

There are two possible ways for a user to fix this.

1. Change the line in makefile.subdirs from @time -f "%e" $< to @time $<. This gives slightly messier output.
2. Download gnu-time from homebrew and change the line to @gtime -f "%e" $<.

Hopefully this note can save someone a bit of time.

[fredrik-johansson]

Is there some easy way to detect OSX in the makefile and then simply change the command to @time $<? Or just run the test without timing output; it's not really essential.