Make sure that the shell tests use the same python interpreter as the
rest of the build instead of picking up `python` from the PATH.
It would be nice if we could use the _disallow helper, but that triggers
on invocations that specify python as the scripting language.
- The register encoding state in the JSON crashlog format changes.
Update the parser accordingly.
- Print the register state when printing the symbolicated thread.
Add a parser for JSON crashlogs. The CrashLogParser now defers to either
the JSONCrashLogParser or the TextCrashLogParser. It first tries to
interpret the input as JSON, and if that fails falling back to the
textual parser.
Differential revision: https://reviews.llvm.org/D91130
