reworked fix for GetEnvironmentStrings/FreeEnvironmentStrings functions
I get a more info about history of GetEnvironmentStrings/FreeEnvironmentStrings
NT 3.1 has GetEnvironmentStrings and FreeEnvironmentStrings is missing
NT 3.51 has GetEnvironmentStrings/GetEnvironmentStringsA/GetEnvironmentStringsW and FreeEnvironmentStringsA/FreeEnvironmentStringsW
Win32s was derived from NT 3.1 but later versions of Win32s have changes from NT 3.51.
This correction use GetEnvironmentStrings for Win32s and NT 3.x and
GetEnvironmentStringsA for higher versions of Windows (9x and NT).
FreeEnvironmentStringsA is used only if available.