gdbserver: boolify and defaultize the 'fetch' parameter of get_thread_regcache

Boolify the 'fetch' parameter of the get_thread_regcache function.

All of the current uses pass true for this parameter.  Therefore, define
its default value as true and remove the argument from the uses.

We still keep the parameter, though, to give downstream targets the
option to obtain a regcache without having to fetch the whole
contents.  Our (Intel) downstream target is an example.

Approved-By: Simon Marchi <simon.marchi@efficios.com>
12 files changed