Drop unused code and always use long long

Drop code left from compatibility with old C++ compilers from before we required C++11.

In particular, we can always use long long now.

assigned to @brad.king

Do: stage

added 5 commits

• a0bd892c - SystemInformation: Use 'long long' unconditionally
• 441dd494 - Drop unused checks for 'long long' and '__int64'
• 2b749749 - Drop unused C type macros check
• 74daf33b - Drop unused Borland and OpenWatcom preprocessor conditions
• c4e8126a - Drop unused CXX cstdio check

Compare with previous version

Do: stage

Do: merge

merged

mentioned in commit a3263389

mentioned in merge request cmake/cmake!4804 (merged)