xtest46: Don't use overlapping array operation.

In this specific case, there is little reason for it not to work,
but druntime checks for overlapping operands in its in contract
anyway.

Fixes the test suite build in debug mode.
return cast(int) msg.wParam in myWinMain; WPARAM is 64bit in Win64 but myWinMain requires an int return value
Merge pull request #1470 from klickverbot/xtest46-array-overlap

xtestt46: Don't use overlapping array operation.
Remove unused strictlyneedmoduleinfo.
Add tvalist for keeping reference of target va_list type.
Merge pull request #1624 from ibuclaw/strictlyneedmodinfo

Remove unused strictlyneedmoduleinfo.
Merge pull request #1623 from ibuclaw/tvalist

Add tvalist for keeping reference of target va_list type.
Merge pull request #1621 from dnewbie/master

update samples/winsamp.d for Win64