Windows dumps have corrupted CONTEXT_RECORD

When we hit an exception in Windows, we get a CONTEXT_RECORD. We then pass this context record to the DBGHelp to print the stack trace. DbgHelp mutates the CONTEXT_RECORD, but we pass the now mutated CONTEXT_RECORD which points to the bottom of the stack instead of the top the stack where the A/V occurs to MiniDumpWriteMinidump. As a result, we get a minidump that points to the wrong place, and is not useful for debugging windows issues.