System libraries are not used when running in a venv

[C0rn3j]

0.9.8b3

Downstream report - Taiko2k/Tauon#1625

I can reproduce this 100% by running Tauon's clean venv script, which does this https://github.com/Taiko2k/Tauon/blob/d09209bd117d6b1d52842a45e06063def2e1051e/run.sh#L55-L84

If I define SDL_BINARY_PATH as /usr/lib, it works.

Forcing SDL_FIND_BINARIES to 1 makes no difference.

The app works just fine outside of the venv.

Tauon additionally sets these:

os.environ["SDL_DISABLE_METADATA"]         = "1" # Disable metadata method,                     "0"        by default.
os.environ["SDL_CHECK_VERSION"]            = "0" # Disable version checking,                    "1"        by default.
os.environ["SDL_CHECK_BINARY_VERSION"]     = "0" # Disable binary version checking,             "1"        by default.
os.environ["SDL_IGNORE_MISSING_FUNCTIONS"] = "1" # Disable missing function warnings,           "0"        by default.