_beginthreadex does not align the stack on 16-byte boundary as expected
On x86 targets, the force_align_arg_pointer attribute may be applied to
individual function definitions, generating an alternate prologue and
epilogue that realigns the run-time stack if necessary. This supports
mixing legacy codes that run with a 4-byte aligned stack with modern
codes that keep a 16-byte stack for SSE compatibility.
Signed-off-by: Aleksey Vasenev <email@example.com>