* This change reduces the total build time from about 14 seconds to about
9 seconds on my computer.
Also:
* Consolidate all the intermediate files into the build directory to
reduces clutter.
* Allow specifying UNIX_ADAPTER_EXE to make. Perhaps this will be helpful
to the MSYS2 fork, which renames console.exe to winpty.exe. (I like
the renaming, but I don't know about the other winpty users. Maybe
I'll make the change after I've put out another stable release...)
* Rename the WINPTY define to COMPILING_WINPTY_DLL define. The longer
name is clearer. I define the macro inside libwinpty/winpty.cc, so the
build system no longer needs to. (I removed the define from
winpty.gyp.)
* Consolidate config-unix.mk and config-mingw.mk into config.mk. The
separation was previously necessary because each file had a conflicting
definition of CXX.
* Rename the UNIX_LDFLAGS_STATIC_LIBSTDCXX macro to UNIX_LDFLAGS_STATIC,
because libstdc++ isn't the only thing I'm linking statically.