The bug originally was discovered in https://bugs.gentoo.org/634190
where complicated callback was returning invalid data on ia64.
This change adds minimal reproducer that fails only on ia64 as:
FAIL: libffi.call/struct10.c -W -Wall -Wno-psabi -O0 execution test
FAIL: libffi.call/struct10.c -W -Wall -Wno-psabi -O2 execution test
FAIL: libffi.call/struct10.c -W -Wall -Wno-psabi -O3 execution test
FAIL: libffi.call/struct10.c -W -Wall -Wno-psabi -Os execution test
Test passes on amd64. The fix is in the following commit.
Bug: https://bugs.gentoo.org/634190
Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>
