* MSYS is 32-bit only.
* MSYS2 and Cygwin are either 32-bit or 64-bit. On 64-bit MSYS2/Cygwin,
we use the same architecture for all generated binaries.
* Prefer mingw-w64 to mingw. mingw-w64 seems to be more up-to-date.
It is the only option for 64-bit Windows, so stop looking for
x86_64-pc-mingw32-g++.
* Also pass -static when linking binaries. Otherwise, a pthreads DLL
is linked dynamically.
* At least for now, I'm shipping Cygwin/MSYS binaries. On Cygwin (but
not MSYS), the console.exe executable previously linked dynamically
to cyggcc_s-1.dll and cygstdc++-6.dll.
Linking dynamically with cygstdc++-6.dll seems risky for a binary
not distributed by Cygwin, because G++'s Windows ABI is unstable, at
least as of G++ 4.7, which turned on the __thiscall calling
convention. If a binary I ship ever comes into contact with a
4.7-versioned cygstdc++-6.dll, then my binary will (very likely)
segfault.
So far, I've only observed this ABI incompatibility with MinGW,
where a sufficiently upgraded MinGW configuration comes with a
libstdc++-6.dll that is completely incompatible with every previous
libstdc++-6.dll, so that every program built against the older
libstdc++-6.dll segfaults immediately. For now, Cygwin seems stuck
at G++ 4.5, and my impression (possibly incorrect), is that G++'s
Windows ABI was stable prior to 4.7. I think G++'s Linux ABI is
stable. Presumably Cygwin will eventually update its compiler,
though, so it makes sense to fix the problem early.
I believe I originally chose to dynamically link the libraries
because it was the default behavior, and I was afraid that a
non-default option would break something. It turns out that
linking statically with cygstdc++-6 *does* break something -- it
causes linker errors if the code uses std::cerr. The workaround
is not to use std::cerr. This is not a problem for the
unix-adapter, which already has to put up with MSYS' gimpy G++ 3.4
compiler.
* Move the Cygwin/MSYS detection logic from config-*.mk into this new
script.
* Recognize either the 32-bit MinGW or the 32-bit MinGW-w64 compiler
driver for Cygwin.
