edbgEcmdDll.C:392:3: error: ‘yaml_parser_t’ was not declared in this scope

[rtds-gary]

Tying to build on x86 ubuntu, but getting error:
ecmd-pdbg-master/src/dll/edbgEcmdDll.C:392:3: error: ‘yaml_parser_t’ was not declared in this scope

My gcc: gcc version 6.5.0 20181026 (Ubuntu 6.5.0-2ubuntu1~16.04)

I originally got a "/ecmd-pdbg-master/src/dll/edbgEcmdDll.C:36:18: fatal error: yaml.h: No such file or directory" error, but googled that and found I should install yaml libs:
$ sudo apt-get install libyaml-dev
$ sudo apt-get install libyaml-cpp-dev

After installing these, the "not declared" error above occurs. Need some help to get past this. Thanks! Gary