Avoid rebuilding libpmc in every incremental rebuild

[arichardson]

Summary

Generate libpmc_events.c in a temporary file first and only overwrite it
if the files are actually different.
This avoids compiling and relinking the different variants of libpmc on
every incremental build.

[jhb]

My only real question is do you want to do a single target? Since you are using mv instead of cp make is always going to invoke both targets anyway. The single target version would just join the two bodies.

lib/libpmc/Makefile

40

Not sure if this should be ${MV} vs mv? (Probably it would in ports, not sure if we add that indirection in src)

[arichardson]

use a single make target

[jhb]

lib/libpmc/Makefile

40

I think you had libpmc_events.c in CLEANFILES in your first version? We probably still want that as well since it's not a checked-in file?

[arichardson]

lib/libpmc/Makefile

40

Ah yes, accidentally dropped that. Will restore before committing.