[ 05:47:53 ume ] ruby18lang An object-oriented interpreted scripting language
Better fix for the problem on AMD64 and Pentium4 since rev1.4.
getcontext() saves EFLAGS and setcontext() restores it. When carry
flag is set in EFLAGS, setcontext() treats it as an system call error.
This problem is filed as misc/92110.
rev1.3 and before hid this problem, and rev1.4 exposed it.
Drop carry flag before getcontext() for workaround for this problem.
Submitted by: Tanaka Akira <akr__at__m17n.org>
Tested by: TAKANO Yuji <takachan__at__running-dog.net>