ISO 9899 7.13.2.1 (3) says that "[...] the values of objects of automatic

storage duration that are local to the function containing the invocation of the
[...] setjmp macro that do not have volatile-qualified type and have been
changed between the setjmp invocation and longjmp call are indeterminate."

As such, we have to mark all variables in a function that uses 'invoke' as
volatile.

This fixes PR77

llvm-svn: 10035