Cygwin: Makefile: build new-cygwin1.dll in a single step

Cygwin: Makefile: build new-cygwin1.dll in a single step

The complicated build routine was only required because we needed
the .cygheap section at the end of the file, and the debug sections
broke this.  Now that the cygheap is out of the way, we really don't
have to do this anymore, and the build can just generate a DLL with
integrated debug info.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>