This reverts commit 2b386b6c80.
This isn't the right approach. Even if the string itself isn't double-freed, it can be returned to the application and then freed while the application is trying to use it. This really needs to be in thread-local storage to be completely safe.
In SDL we already have a global thread-local error string, so I'm going to make an SDL-specific change to handle the error strings safely.
Simple DirectMedia Layer is a cross-platform development library designed
to provide low level access to audio, keyboard, mouse, joystick, and graphics
hardware via OpenGL and Direct3D. It is used by video playback software,
emulators, and popular games including Valve's award winning catalog
and many Humble Bundle games.
More extensive documentation is available in the docs directory, starting
with README.md