This patch helps add the missing context IsGNUStyle. Before this patch, yaml2obj cannot parse the YAML description of 'debug_gnu_pubnames' and 'debug_gnu_pubtypes' correctly due to the missing context.
In other words, if we have
DWARF: debug_gnu_pubtypes: Length: TotalLength: 0x1234 Version: 2 UnitOffset: 0x1234 UnitSize: 0x4321 Entries: - DieOffset: 0x12345678 Name: abc Descriptor: 0x00 ## Descriptor can never be mapped into Entry.Descriptor
yaml2obj will complain that "error: unknown key 'Descriptor'".
This patch helps resolve this problem.