Also replace boost::detail::atomic_exchange_and_add for the interpreter.

Generalize the __cxa_atexit replacement to cover more symbols.
Because the JIT cannot handle inline asm, provide compiled symbols for relevant
functions until cling has switched to MCJIT.
This fixes the use of many boost libraries (e.g. regex) in cling on x86_64/i386.
Kudos to Marco Clemencic for the idea!