in case we have gmake >= 3.80 we can use the new | (order) syntax where
all dependencies after the | are required to be there but not trigger
execution of the rule. This should greatly enhance the build experience
on Win32 and AIX (platforms that need the EXPLICITLINK option).


git-svn-id: http://root.cern.ch/svn/root/trunk@13584 27541ba8-7e3a-0410-8455-c3a389f83636