Rework try macros to simplify setjmp expression.
Rework try macros to simplify setjmp expression.

According to spec, setjmp is only allowed to be called in very restricted
contexts. A comma expression is not one of them; which puts it in danger
of compiler optimizations going wrong.

ccxvii/mujs,ccxvii/mujs,ccxvii/mujs,ccxvii/mujs