[sanitizer_common] Fuchsia-specific symbolizer

Summary:
Fuchsia doesn't support built-in symbolization per se at all.
Instead, it always emits a Fuchsia-standard "symbolizer markup"
format that makes it possible for a post-processing filter to
massage the logs into symbolized format.  Hence, it does not
support user-specified formatting options for backtraces or other
symbolization.

Reviewers: vitalybuka, alekseyshl, kcc

Subscribers: kubamracek, mgorny, phosek, filcab, llvm-commits

Tags: #sanitizers

Differential Revision: https://reviews.llvm.org/D36032

llvm-svn: 309760