For Windows 3.1, use GetProcAddress to call GetEnvironmentStrings(A) and FreeEnvironmentStringsA

GetEnvironmentStringsA() returns NULL under Windows 3.1, to get the environment block you must call GetEnvironmentStrings(). GetEnvironmentStringsA/FreeEnvironmentStringsA entry points do not exist in Win32s v1.15 and earlier, using GetProcAddress allows us to run in that environment anyway.