This will allow x86-64 to shrink its exception tables by half, and ia64 to
drop its custom implementation.
1/3: x86-64: use macros to generate exception table entries
2/3: x86-64: use relative 32-bit pointers in exception tables
3/3: ia64: drop custom exception table implementation
Signed-off-by: Jan Beulich <[email protected]>