[Windows] Use llvm-symbolizer before using dbghelp

Summary:
llvm-symbolizer understands both PDBs and DWARF, so it's a better bet if
it's available. It prints out the function parameter types and column
numbers, so I needed to churn the expected test output a bit.

This makes most of the llvm-symbolizer subprocessing code
target-independent. Pipes on all platforms use fd_t, and we can use the
portable ReadFromFile / WriteToFile wrappers in symbolizer_sanitizer.cc.
Only the pipe creation and process spawning is Windows-specific.

Please check that the libcdep layering is still correct. I don't know
how to reproduce the build configuration that relies on that.

Reviewers: samsonov

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D11791

llvm-svn: 244616