Well I did find your RCBot1 src code that was edited and modified for SC 4.5 around 2010, if I am not mistaken but I think I've managed to recompile and did some minor fixes for SC 5. I believe that SC 5 uses from their server /dlls folder like server.dll and server.so - rather than hl_i386.so and hl.dll that requires a fix for RCBot from the bot.h file at line 6322. Also I know that Metamod needs to be updated and compatible with SC 5, including the Metamod-P modified version that appears to have some problems at the moment.
So I thought I maybe recompile those bots for both Metamod and Stand-Alone SC 5. I cannot guarantee nor promise those bots will work but it appears fine on testing it on DMC Linux server. Those bots were recompiled with VS2017 and Clang++ v3.8 with G++ 5.4. Don't gets your hopes up just yet apart from trying those bots out:
https://www.dropbox.com/s/p3hpeytdd5...a_sc5.zip?dl=0