I moved all of the Transforms passes to lib/Transforms/NaCl. It is currently build and linked twice by Emscripten. At some point I'd like to merge this pass with ExpandLargeIntegers, since both do redundant work.

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Variadic macros need at lest one variadic argument (## is a GCC extension).
Some unused local variables.
Casting away const-ness (need const_cast then static_cast).
No need to do 'if (X) free(X);' since free(0) is valid.
Simplify away some (void*) voodoo.

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…382.

kripken added this in 6198caf but it's not needed anymore (and was incorrect): the code was putting varargs on the stack as a packed struct which caused misaligned reads and writes, I fixed the issue by making the struct non-packed and using the target's prefered alignment for each element instead. The alloca should be aligned to the target's preference too, so everything should now be neatly aligned. This pass runs pre-opt, so the optimizer can figure out the alignment of all the loads and stores and foster further harmony in the memory.

Dan added this change in 338da97 before ExpandVarArgs used IRBuilder. Now that it uses IRBuilder the change isn't needed because it'll automatically create constexprs when it can.

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…+ an offset