Build fails with parentheses in DESTDIR

If DESTDIR has parentheses in it, the build fails.

• create a new lib with the wizard
• add the following to the .pro:

  DESTDIR = "$$shadowed($$PWD)/../foo (bar)"
  

Trying to build it fails:

/bin/sh: -c: line 0: syntax error near unexpected token `('
/bin/sh: -c: line 0: `test -d ../foo\ (bar)/ || mkdir -p ../foo\ (bar)/'
make: *** [../foo (bar)/libtestlib.1.0.0.dylib] Error 2

This is because the generated makefile rules aren't quoted/escaped properly:

../foo\ (bar)/libtestlib.1.0.0.dylib:  $(OBJECTS) $(SUBLIBS) $(OBJCOMP)  
	@test -d ../foo\ (bar)/ || mkdir -p ../foo\ (bar)/

Workaround is obviously to take out the parens, but it should work with them.