Revert "gfxlib2: Add LONGINT overload for screeninfo()"

This reverts c8b85545 and partially fixes #704. Adding the 2nd screeninfo()
overload broke code that uses only its string parameter and doesn't specify
any arguments for the Long/LongInt parameters, because then the compiler
cannot decide which overload to call anymore.
tests: Add regression test for #704
gfxlib2: Turn screeninfo()'s Long parameters into Integers

in the hopes that this is better for 64bit than Longs. Part 2 of the fix
for #704.

Longs will be 32bit while Integers are 64bit, so they're incompatible as
far as screeninfo()'s Byref parameters are concerned. Integers are probably
more common/standard, so it makes sense to use them.
Revert "gfxlib2: Add LONGINT overload for getjoystick()"

This reverts bbf526c3, same problem as with screeninfo() in 57335003.
tests: Add similar regression test for getjoystick()
gfxlib2: Turn getjoystick()'s Long parameter into an Integer

see also 5f2f62ea.