Make sure that the following SymbolFileDWARF functions can handle getting a...

Make sure that the following SymbolFileDWARF functions can handle getting a lldb::user_id_t for another SymbolFileDWARF:

CompilerDecl
SymbolFileDWARF::GetDeclForUID (lldb::user_id_t type_uid);

CompilerDeclContext
SymbolFileDWARF::GetDeclContextForUID (lldb::user_id_t type_uid)

CompilerDeclContext
SymbolFileDWARF::GetDeclContextContainingUID (lldb::user_id_t type_uid)

Type*
SymbolFileDWARF::ResolveTypeUID (lldb::user_id_t type_uid)

<rdar://problem/25592223>

llvm-svn: 267494