v68k:  Make BKPT vector an argument, not an index

Axe the bkpt_handlers struct and just use a single function that takes a
vector argument, and make the function an optional parameter.
[FIX] v68k/t:  Make tests buildable again
v68k-swap:  Fix broken CCR check on SWAP test

SWAP does a basic CCR update.
v68k-div:  Fix Division By Zero's exception vector
v68k-bitop:  Fix bit-operation opcodes

They were each off by 0x40.
v68k-exceptions:  Fix MOVE SR opcode
v68k-exceptions:  Fix BKPT test cases
v68k-core:  Fix BKPT test cases
v68k-core:  Use v68k::low_memory_region

Otherwise, the prefetch from address 0 succeeds and the test fails.
Merge branch 'fix-v68k-tests'