windows: define __USE_MINGW_ANSI_STDIO for all Windows compilers.
stmhal: Allow network, uselect, usocket mods to be used by other ports.

Remove include of stm32f4xx_hal.h, replace by include of MICROPY_HAL_H
where needed, and make it compile without float support.  This makes
these 3 modules much more generic and usable by other ports.