Make qstr generation depend on modifications in mpconfigport.h, mpconfig.h
and makeqstrdata.py and if any of those change scan all source files for
qstrs again since they might have changed (for example typcially when
enabling new features in mpconfig.h).
This fixes #2982 for msvc builds.

It is not used anywhere and causes a warning about redefinition because
it is used in modutimeq.c

The standard preprocessor definition to differentiate debug and non-debug
builds is NDEBUG, not DEBUG, so don't rely on the latter:
- just delete the use of it in objint_longlong.c as it has been stale code
  for years anyway (since commit [c4029e50]): SUFFIX isn't used anywhere.
- replace DEBUG with MICROPY_DEBUG_NLR in nlr.h: it is rarely used anymore
  so can be off by default

But warn if anything else but host/port is passed.

Similar to the implementation added to unix port module previously.

This follows previous refactor made to unix/moduselect.

extmod/crypto-algorithms/sha256.c was recently fixed so that it didn't
include this header.

Otherwise, if we already have a packet in progress, finish it first, before
check "peer closed" status.

It doesn't do anything.  The VFS feature is controlled by MICROPY_VFS and
the FatFS driver, by MICROPY_VFS_FAT (which are set in mpconfigport.h).

As there's no networking support in mainline yet, networking is disabled,
because otherwise the board hangs on startup.

The trailing zeros should be truncated from the converted value.

This patch allows the following code to run without allocating on the heap:

    super().foo(...)

Before this patch such a call would allocate a super object on the heap and
then load the foo method and call it right away.  The super object is only
needed to perform the lookup of the method and not needed after that.  This
patch makes an optimisation to allocate the super object on the C stack and
discard it right after use.

Changes in code size due to this patch are:

   bare-arm: +128
    minimal: +232
   unix x64: +416
unix nanbox: +364
     stmhal: +184
    esp8266: +340
     cc3200: +128

This patch refactors the handling of the special super() call within the
compiler.  It removes the need for a global (to the compiler) state variable
which keeps track of whether the subject of an expression is super.  The
handling of super() is now done entirely within one function, which makes
the compiler a bit cleaner and allows to easily add more optimisations to
super calls.

Changes to the code size are:

   bare-arm: +12
    minimal:  +0
   unix x64: +48
unix nanbox: -16
     stmhal:  +4
     cc3200:  +0
    esp8266: -56

If we get to this point in the code then pn_iter is guaranteed to be a
struct.

Prior to making this a config option it was previously available on these
(and all other) ports, and it makes sense to keep it enabled for mpy-cross
as well as ports that have a decent amount of space for the code.

With this optimisation enabled the compiler optimises the if-else
expression within a return statement.  The optimisation reduces bytecode
size by 2 bytes for each use of such a return-if-else statement.  Since
such a statement is not often used, and costs bytes for the code, the
feature is disabled by default.

For example the following code:

    def f(x):
        return 1 if x else 2

compiles to this bytecode with the optimisation disabled (left column is
bytecode offset in bytes):

    00 LOAD_FAST 0
    01 POP_JUMP_IF_FALSE 8
    04 LOAD_CONST_SMALL_INT 1
    05 JUMP 9
    08 LOAD_CONST_SMALL_INT 2
    09 RETURN_VALUE

and to this bytecode with the optimisation enabled:

    00 LOAD_FAST 0
    01 POP_JUMP_IF_FALSE 6
    04 LOAD_CONST_SMALL_INT 1
    05 RETURN_VALUE
    06 LOAD_CONST_SMALL_INT 2
    07 RETURN_VALUE

So the JUMP to RETURN_VALUE is optimised and replaced by RETURN_VALUE,
saving 2 bytes and making the code a bit faster.

Otherwise the type of parse-node and its kind has to be re-extracted
multiple times.  This optimisation reduces code size by a bit (16 bytes on
bare-arm).

PN_atom_expr_normal parse nodes always have structs for their second
sub-node, so simplify the check for the sub-node kind to save code size.

Saves code size (20 bytes on bare-arm) and makes it a tiny bit more
efficient.

Add definitions/source files for features which work on the windows
ports but weren't yet enabled.
UTIME related lines are moved a couple of lines up to make comparision
with unix/mpconfigport.h easier in the future.

With 30-bit floats there aren't enough bits to faithfully print 7 decimal
digits, so reduce the precision to 6 digits.

Sometimes when setting a channel callback the callback fires immediately,
even if the compare register is set to a value far into the future. This
happens when the free running counter has previously been equal to what
happens to be in the compare register.

This patch make sure that there is no pending interrupt when setting a
callback.

It controls the character that's used to (asynchronously) raise a
KeyboardInterrupt exception.  Passing "-1" allows to disable the
interception of the interrupt character (as long as a port allows such a
behaviour).