TODO tasks
==========
+configure: Add -D GC_DLL if shared library (at least for mingw/cygwin).
+And remove Makefile.DLLs.
+
Add "Disclaim" functionality (merge with paurkedal-disclaim).
tests/CMakeLists.txt: Add more executables (see tests.am).
gc.mak.)
Makefile.dj: Remove if it is possible to use auto-generated Makefile instead.
-(Same for EMX_MAKEFILE, Makefile.DLLs.)
+(Same for EMX_MAKEFILE.)
build_atomic_ops.sh[.cygwin]: Remove if really not needed.