[PDB] Support PDB-backed expressions evaluation (+ fix stuck test)

Summary:
This patch contains several small fixes, which makes it possible to evaluate
expressions on Windows using information from PDB. The changes are:
- several sanitize checks;
- make IRExecutionUnit::MemoryManager::getSymbolAddress to not return a magic
  value on a failure, because callers wait 0 in this case;
- entry point required to be a file address, not RVA, in the ObjectFilePECOFF;
- do not crash on a debuggee second chance exception - it may be an expression
  evaluation crash. Also fix detection of "crushed" threads in tests;
- create parameter declarations for functions in AST to make it possible to call
  debugee functions from expressions;
- relax name searching rules for variables, functions, namespaces and types. Now
  it works just like in the DWARF plugin;
- fix endless recursion in SymbolFilePDB::ParseCompileUnitFunctionForPDBFunc.

Reviewers: zturner, asmith, stella.stamenova

Reviewed By: stella.stamenova, asmith

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D53759

llvm-svn: 348136