specifically, we need it iff the user gets to see the stopped inferior

seems to have been an artifact from an early version. it was
unreachable (gdb going wild notwithstanding), and would do
Strange Stuff (TM) if it ever were reached.

first, try harder to have an up-to-date sources list.
then, use the mapping whenever applicable and available.

when queuing up commands, don't interrupt if we are already waiting
for interruption. that will be the case when other commands area already
queued.

if there are already commands queued for running after temporary break,
then *all* commands must queued up or their order will change.

*in theory*, there is no way we could at any point know more than gdb
knows and tells us about full path names. let's see what practice shows
for the gdbs we support ...

and fix typo in debug message :)=

this is an epic fail for older gdbs which don't report library events,
but at least we tried.

in theory, we should support fsf gdb on apple now.
this also cleans and documents some execution paths.

e.g., when the engine is not ready

these missed the handleExecContinue() callback, so they got missed last
time. added both callback and flag, and some more glue to the gross
isBogus hack.

as it turns out, it is not possible to set pending breakpoints until
gdb has loaded as image. so add some hooks to enable adapters to trigger
the initial breakpoint syncing at the right time. do not add additional
states (say, InferiorPreparing), as it would just complicate things.

this includes:
- move the gdb ownership back to the engine (thus strip down the
  adaptors as far as possible)
- make gdb startup synchronous
- make adapter shutdown synchronous
- fix the state transitions relating to shutdown

Reviewed by: Friedemann Kleint

This should save debugger round trips and crashes in the debugging
helpers.
Add respective option to debugging helper option page, defaulting to
true.On this occasion, make CDB detect shadowed variables correctly
and display them as "<shadowed n>" as does the Gdb engine by
reversing the direction in which
CdbSymbolGroupContext::populateINameIndexMap works.
Rubber-stamped-by: hjk <qtc-committer@nokia.com>

specifically, this will skip the initial stop at _start when using the
terminal and remote adapters.