- Let the build environment decide about the toolchain to be used, in case
  there are special tweaks and paths to be considered. Just provide some
  defaults, in case the values are undefined.
- py-version.sh does not need any bash specific features.
- Use libdl only on Linux for now. FreeBSD provides dl*() calls from libc.
- FreeBSD provides alloca() via stdlib.h, in contrast to Linux and Windows
- Move the includes for alloca() intp mpconfigport.h
- Cast the struct stat sb.st_ino field to machine_int_t explicitly to avoid a
  cast error in MP_OBJ_NEW_SMALL_INT(). This is necessary for FreeBSD, where
  st_ino is of different size
- If MP_CLOCKS_PER_SEC is defined on the target host, simply define CLOCK_DIV
  as a fraction, regardless of the value of MP_CLOCKS_PER_SEC.
  FreeBSD uses a non-POSIX compliant value of 128 for CLOCKS_PER_SEC
Merge pull request #674 from marcusva/fbsd-patches

Build patches for FreeBSD (as discussed in the former pull request #666)
Merge pull request #672 from marcusva/makefile

toolchain fixes to enable cross compatibility
py, mk: Revert change where build variables set with ?=.

?= operator does not do delayed expansion (unlike =).
py: Merge mp_execute_bytecode into fun_bc_call.

This reduces stack usage by 16 words (64 bytes) for stmhal/ port.

See issue #640.
py: Add generic mp_not_implemented() func to use instead of assert().

Benefits: won't crash baremetal targets, will provide Python source location
when not implemented feature used (it will no longer provide C source
location, but just grep for error message).
modsys: Add optional support for sys.platform.

Ports which wants to have it, should define MICROPY_PY_SYS_PLATFORM to a
string value they need.
py: Implement default keyword only args.

Should finish addressing issue #524.
objtype: Enable __lt__ method support for instances.
Merge branch 'master' of github.com:micropython/micropython

Conflicts:
	py/emitglue.c
py: Make sure getattr() works with non-interned strings (by interning them).
tests: Fix default arg test.
py: Simplify function call of a bytecode object.
tests: Add more tests for default keyword-only args.
Merge branch 'alloca' of github.com:marcusva/micropython into marcusva-alloca
Provide definition of alloca() in mpconfigport.h.
Merge branch 'marcusva-alloca'
tests: Run 'micropython' tests on pyboard.