MinidumpParsing: pid, modules, exceptions, strings

Summary:
Added parsing of the MiscInfo data stream.
The main member of it that we care about is the process_id
On Linux generated Minidump (from breakpad) we don't have
the MiscInfo, we have the /proc/$pid/status from where we can get the
pid.
Also parsing the module list - the list of all of the loaded
modules/shared libraries.
Parsing the exception stream.
Parsing MinidumpStrings.

I have unit tests for all of that.
Also added some tests using a Minidump generated from Windows tools (not
from breakpad)

Reviewers: labath, zturner

Subscribers: beanz, lldb-commits

Differential Revision: https://reviews.llvm.org/D24385

llvm-svn: 281348