Platform: add totalRAM.

[saurtron]

Work done

• Add Platform.totalRAM to get total system ram as a number in MB.

Related issues

• Fixes Add Platform.AvailableRAM #1640
  • not the same name but imo AvailableRAM or FreeRAM should be reserved for smth else reporting actual free ram, that seems a bit trickier tho and possibly not so useful because the number could be misleading, so for now just adding TotalRAM.

Remarks

• I see games having to parse the hardware string, that seems awkward and fragile.
• Not sure if I'm using the best approach here, _SC_PHYS_PAGES is not POSIX standard, but I hope it won't be a problem. It does seem to be supported in freebsd as well as linux.

[sprunk]

Fixes #1640

[sprunk]

• would be nice to avoid #ifdef _WIN32 and to instead put code in /rts/System/Platform/Win/*.cpp.
• there is already some code that gets total RAM, would be good to avoid duplicate code. Figure out if there are behaviour differences and document them, otherwise if the behaviour is the same refactor the existing code so the same source of truth is used both for infolog.txt printing and for the new Lua var:
  

  spring/rts/System/Platform/Misc.cpp

  Lines 435 to 437 in 42822a4

  	if (memInfo != nullptr) {
  	while (fgets(buf, sizeof(buf), memInfo) != nullptr) {
  	if (strstr(buf, "MemTotal") != nullptr) {

  
  

  spring/rts/System/Platform/Win/WinVersion.cpp

  Lines 328 to 332 in 42822a4

  	MEMORYSTATUSEX statex;
  	constexpr int div = 1024 * 1024;
  	statex.dwLength = sizeof(statex);
  	GlobalMemoryStatusEx(&statex);

[saurtron]

• would be nice to avoid #ifdef _WIN32 and to instead put code in /rts/System/Platform/Win/*.cpp.
• there is already some code that gets total RAM, would be good to avoid duplicate code. Figure out if there are behaviour differences and document them, otherwise if the behaviour is the same refactor the existing code so the same source of truth is used both for infolog.txt printing and for the new Lua var:

Done, lemme know if there's anything else you'd like changed.