Add missing mdoc_handler for .ll macro.

ok pedro@
Add text production macro for Bitrig (.Br).

ok pedro@
Our size_t's are unsigned long, so make ARM use that on AAPCS, too.

ok drahn@
Add patch for size_t commit in llvm.
For now, use SJLJ Exceptions on ARM.  This will prolly change soon.

ok drahn@
Add patch for llvm sjlj commit.
Compare MK_ARM_EABI in lower-case.

Diff from and ok drahn@
In kernelland the required aeabi functions can use the code we already have.

ok drahn@