Fix for readlink on Linux in cctools
Remove dodgy ldclassic test and disable it always.

It's deprecated by ld64 so best not bother.
The test for it was a huge pile of rubbish
too, determining the value of sizeof(long)
and creating a file called =8 in builddir.

Conflicts:
	cctools2odcctools/files/configure.ac
Add -D_GNU_SOURCE to CFLAGS/CXXFLAGS for MinGW-w64