Update tools.mk

Download directory/file changed for openssl windows version.
PIOS COM: make the interface thread safe

Currently the interface to the FIFO buffer is not thread
safe for multiple threads sending and receiving. This adds
a semaphore on those interfaces.
Merge pull request #1180 from joergrohde/patch-1

Update tools.mk
Android: add serial support for FTDI_FT230X

This is the chipset used in the 3dr radio v2 and should
add support for that radio.
Merge pull request #1187 from peabody124/ftdi_pid

Android: add serial support for FTDI_FT230X
Merge pull request #1181 from peabody124/pios_com_thread

PIOS COM: make the interface thread safe
Sparky: check in assembly page
Merge pull request #1186 from peabody124/sparky_assembly

Sparky: check in assembly page
MiniM4: initial commit of new target

Basic support for new Mini-M4 board.
Work in progress, not working yet.
MiniM4: Clean-up and initial MPU6050 support

Clean-up of various files, initial changes for U2C and MPU6050 support
on MiniM4 board.