This came up while I was re-installing my operating system. So the same code, but a more-or-less fresh install (Pop OS 22.04 LTS).
After that, I got errors for missing packages when compiling the 'imgui' example:
I figured out that I had previously installed these packages when setting up raylib. Once I installed the listed packages (Ubuntu, in my case) I could compile and run as before.
https://github.com/raysan5/raylib/wiki/Working-on-GNU-Linux
sudo apt install build-essential git
sudo apt install libasound2-dev libx11-dev libxrandr-dev libxi-dev libgl1-mesa-dev libglu1-mesa-dev libxcursor-dev libxinerama-dev libwayland-dev libxkbcommon-dev
(some of these may not be necessary)
I suggest including something similar in the README.md, as it might help people out getting started.