Revert "[jit] Align the stack in mono_arch_restore_context () on x86 since it might be unaligned if it was captured asynchronously."

Fixes: https://bugzilla.xamarin.com/show_bug.cgi?id=17410

This reverts commit 7798b94706e5552cd1abd80227631f3f9b1bfdad.

Commit 7798b947 caused Bug #17410; revert to fix.
[corlib] Mark awaited task exception observed when GetResult does the wait