* lily/main.cc (setup_paths)[!__MINGW32__]: Bugfix: if argv0 is

* lily/main.cc (setup_paths)[!__MINGW32__]: Bugfix: if argv0 is
not absolute, make it absolute using PATH.

* python/midi.c (initmidi): Fix type for mingw.

* stepmake/stepmake/compile-vars.make (SHARED_FLAGS): Support mingw.

* stepmake/stepmake/generic-vars.make (MINGW_BUILD): Detect mingw
cross compiling.

* stepmake/aclocal.m4: Support python cross compiling.

* stepmake/stepmake/python-module-vars.make (SHARED_MODULE_SUFFIX):
Add mingw section.