Added printf source from musl c library
Added files from micropython to test stm board
Merge branch 'master' into test
Added more files from micropython to test on stm board

Made some modifications to make a minimal build.  This minimal
build does not include any python type code or the storage device.

The goal is to create a binary that builds and links with the
micromusl c library and provides enough functionality to do
unit tests on the c library functions with the micropython stm
board.
Modified stm-test Makefile to include libgcc.a

Including this runtime library should be covered under the
GCC Runtime Library Exception
Added strerror from musl c library

This is required for strerror and __errno_location
Removed reference to pthread.h in __errno_location.c

Since micromusl doesn't support threads, there is no
need to have a seperate errno for each thread.
Remove LICENSE file created by github on initial import

The license is covered in the README.md and COPYRIGHT files imported
from the musl library.
Added complex.h and frexpl.c from musl library

Required to get printf working.
Added frexp.c from musl library

Required to get printf working
Add wcrtomb.c and wctomb.c from musl c library

Needed for printf function
Add stdout.c from musl c library

Required for printf
Add __towrite.c and fwrite.c from musl c library

Required for printf
Add __stdio_exit.c from musl library

Required for printf
Removed __aeabi_f2d and __aeabi_d2f from main.c in stm-test

These are now provided by libgcc.a
Changed compile flags in Makefile to be compatible with libgcc.a

libgcc.a that comes with gcc-arm-none- is compiled with these flags
Remove __lock from stdio_exit

Since micromusl is not threaded, this lock is not required.
Add __lockfile from musl c library
Remove threaded locking code from __lockfile.c