[Qt-interest] qmake and external libraries

[Manuel Argüelles]

Hello,

Is it possible to check for the presence of a library and define a macro 
if found? like (HAVE_MYLIB)?

I have been reading the qmake manual but couldn't find anything clear 
about this, it seems that there's something for pkg-config libraries, but 
the library I'm trying to use does not provides a .pc file.

I would like to make this as an optional feature, in the way that if the 
end user has the library (shared object or dll) I can enable the feature, 
if not the user will still be able to compile and use the application but 
without that feature. (that's why I need the define)

I know this can be done with gnu build system, but I just want to be sure 
that in fact I have to use the gnu build system for this, and if so how 
does qmake plays with it?

If there any projects or examples that I can look at?

Thanks