Versioning *should* not be an issue. I have used it in several projects making use of shared libraries and it worked just fine without requiring any trick...

AFAIK the following will always work, no matter the versioning :
Qt Code: 
  1. LIBS += -lmylib
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Because the linker (is supposed to) take care of adding prefix/suffix/versioning to match the platform specific conventions when it searches for a matching shared lib.

The only issue I can see in your pro is the space in the LIBS assignement. It ought to be written like that :
Qt Code: 
  1. LIBS += -L../mylib
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