Fix C macros madness
Wouldn't it be better to only test one macro? At ECL build time both are available: cygwin thanks to the configure magic, and CYGWIN if a sensible compiler is used. When building against ECL, only CYGWIN will be (or nothing if using a mean compiler). Ok this only matters in config.h, but... Or you could imagine that " "define some_macro_for_cygwin" is written in config.h at configure time if cygwin is defined. This would let programs build against ECL with compiler not defining CYGWIN. And in fact that's not really clever, because if you compile from another environment and link to ecl which links to cygwin, you might not want to directly link to cygwin... So all of this looks complicated, whereas only using CYGWIN at ECL build time and in config.h seems fine as well.
By the way, this is also true for MinGW32, in the source code both tests on mingw32 (which is only available at build time, defined by configure) and MINGW32 are used.