Emulating GNU Make conditionals, or: Is there a nice way to automatically set CFLAGS when make is run?

[Dalibor Topic]

Hi all

I have a problem converting an old code base to GNU Automake, in that 
the developers are used to spicing up their GNU Makefiles with GNU Make 
conditionals, that are evaluated when make is run, in order to have some 
shortcut options for setting CFLAGS.

They use make -DCHECK=1 to enable adding of special debuggin flags, for 
example, and make -DPROF=1 to add another set of flags to enable a build 
fro profiling.

Is there a (better) way to do that using GNU Automake? I'be been 
browsing the archives for a while but couldn't find anything.

cheers,
dalibor topic