[PCH] Make sure that the SourceExpr of a OpaqueValueExpr is always initialized
when deserialized, fixing random crashes in libclang.

Also simplifies how OpaqueValueExprs are [de]serialized.
The reader/writer automatically retains pointer equality of sub-statements (when a
statement node is referenced in multiple nodes), so no need to manually handle it.

llvm-svn: 145752
5 files changed
tree: 26df581083fe6dfd8927854db7eed0fb046c895a
  1. clang/
  2. compiler-rt/
  3. debuginfo-tests/
  4. libcxx/
  5. libcxxabi/
  6. lldb/
  7. llvm/
  8. polly/