This is to get the test suite running and passing.

Otherwise, os.uname() returns empty string for SDK version.

For some reason, Travis now has Google Chrome PPA included in the builder
image, that lacks i386 arch, that leads to apt-get update error. So, ignore
it (this is not ideal as may lead to actual repo update failures to be missed,
leading to installation of old package, leading to weird errors; let's keep
that in mind).

No complex numbers though.

Moved from stmhal.

Based on stmhal implementation - rather small, so just duplicating.

This component allows to generate .mpy files (pre compiled bytecode)
which can be executed within any MicroPython runtime/VM.

This new compile-time option allows to make the bytecode compiler
configurable at runtime by setting the fields in the mp_dynamic_compiler
structure.  By using this feature, the compiler can generate bytecode
that targets any MicroPython runtime/VM, regardless of the host and
target compile-time settings.

Options so far that fall under this dynamic setting are:
- maximum number of bits that a small int can hold;
- whether caching of lookups is used in the bytecode;
- whether to use unicode strings or not (lexer behaviour differs, and
  therefore generated string constants differ).