The main aim of these changes is to support `ret` instructions (that are
indirect jumps), so that function calls can now work properly.
* Emit a dummy call to a `@newPC` function to record where a new
instruction in the original assembly started, what is its PC and its
size. The `Size` parameter for these function call is initially zero,
and it's updated later when a new instruction is met or the current
basic block is terminated. All these calls, before the final emission
of the IR are removed `InstructionTranslator::removeNewPCMarkers`.
* Transform translateMoveToPC into an LLVM pass
(`TranslateDirectBranchesPass`).
* Implement `getNextPC`, which returns the next program counter by
looking for a call to `@newpc` in the current basic block, and,
recursively, in all the basic blocks dominating the current one. This
function is used to force exploration of the basic block coming after
a direct jump, which is paritcularly useful in case of a function call.
* Introduce `translateIndirectJumps`, which translates all the leftover
writes to the PC, i.e. all the indirect ones, by diverting execution
to a large switch statement mapping addresses in the original program
to the corresponding basic blocks in the translated program.
* Introduce `function_call`, a simple test for function calls.
* Other minor changes and whitespace fixes.
Alessandro Di Federico