stdio.h was included in all HAL files only to provide
definition of NULL symbol
"stdio.h" includes "types.h" which contains some conflicting definitions
with "drivers/cc3000/inc/socket.h"
HAL Driver before v1.4.2 had a bug which caused clearing all pending
flags in MSR, TSR, RF0R and RF1R instead of only the requested one.
This is why micropython got away without explicitly clearing flags
in IRQ handler.
Current version of HAL drivers optimize IRQ handler by using precalculated
DMA register address and stream bitshift instead of calculating it on every interrupt.
Since we skip call to `HAL_DMA_Init` on reused DMA, fields StreamBaseAddress and StreamIndex
of DMA handle are not initialized and thus leads to SegFault in `DMA_IRQHandler`.
HAL_DMA_Init is a big routine and we do not need to call it on each use of DMA
(ex.: series of I2C operations) and DMA_CalcBaseAndBitshift is really small and
releasing it increases code size by only 8 bytes.
If a port defines MICROPY_READER_POSIX or MICROPY_READER_FATFS then
lexer.c now provides an implementation of mp_lexer_new_from_file using
the mp_reader_new_file function.