adb: handle some edge cases with process environments.

    // Construct the environment for the child before we fork.

    passwd* pw = getpwuid(getuid());

    std::unordered_map<std::string, std::string> env;

    if (environ) {

        char** current = environ;

        while (char* env_cstr = *current++) {

            std::string env_string = env_cstr;

            char* delimiter = strchr(env_string.c_str(), '=');

            // Drop any values that don't contain '='.

            if (delimiter) {

                *delimiter++ = '\0';

                env[env_string.c_str()] = delimiter;

            }

        }

    }

    if (pw != nullptr) {

        // TODO: $HOSTNAME? Normally bash automatically sets that, but mksh doesn't.