Adds a check to avoid symbolization when printing stack traces if the
stack_trace_format flag does not need it. While there is a symbolize
flag that can be turned off to skip some of the symbolization,
SymbolizePC() still unconditionally looks up the module name and offset.
Avoid invoking SymbolizePC() at all if not needed.
This is an efficiency improvement when dumping all stack traces as part
of the memory profiler in D87120, for large stripped apps where we want
to symbolize as a post pass.
Differential Revision: https://reviews.llvm.org/D88361
Teresa Johnson