Warning about debugging optimized code was not happening without dSYMs. Now it...

Warning about debugging optimized code was not happening without dSYMs. Now it works for DWARF in .o files on Darwin.

I changed "m_is_optimized" in lldb_private::CompileUnit over to be a lldb::LazyBool so that it can be set to eLazyBoolCalculate if it needs to be parsed later. With SymbolFileDWARFDebugMap, we don't actually open the DWARF in the .o files for each compile unit until later, and we can't tell if a compile unit is optimized ahead of time. So to avoid pulling in all .o right away just so we can answer the questions of "is this compile unit optimized" we defer it until a point where we will have the compile unit parsed.

<rdar://problem/26068360> 

llvm-svn: 274585