Clear all allocated bytes in ByteArray::create

This makes sure there are no non zero bytes in the resulting memory,
which could result in information leakage for example that people would
not expect.
Use a larger stack buffer when filling IOBuffer

Increases performance of reading IO, for example for File.read
Introduce ByteArray::create_dirty and use where safe

This allocates a ByteArray without zero'ing all the memory. This is for
example useful when used in String::create, where the memory will be
overwritten anyway. Other cases are where ByteArray used as backing
store for Bignum and Regexp.
Increase default IOBuffer size to 32k

Results in another significant performance increase for File.read, since
it has to flush the buffer fewer times.
Don't include llvm/Module.h twice
Sort LLVM includes for coming LLVM 3.3 support
Fix building for LLVM from source

Also removes old unused debugging tasks and uses system() like Daedalus
does.
Switch to LLVM 3.2 as the default for prebuilts

There are now prebuilt LLVM images for OS X 10.6, 10.7, 10.8 and Linux
versions based on GCC 4.1, 4.2, 4.3, 4.4, 4.5, 4.6 and 4.7, both for
i686 and x86_64 architectures. This should cover most of the systems
that people use.
Make error message more explicit about what the problem is

Apparently it still wasn't clear what the issue was, given we still got
issues opened on this problem. Make it even more explicit so people
hopefully read it all now and know how to solve it.
Use inflation functions consistently

We don't pass down the objectmemory to other similar methods, so don't
do it for this one either. Also move find_index to the header so it can
be inlined in places where it's used.
Use set inflated header helper where appropriate

We can use the set_inflated_header method in these two places instead of
writing the same code manually.
Plug memory leaks of DIBuilder

Checked with LLVM 3.0, 3.1, 3.2, 3.3
Merge pull request #2244 from ryoqun/dibuilder-memory-leak

Plug memory leaks of DIBuilder
Fix JIT debugging output for ivar reads and writes
Failing spec for __method__ in class body
Add tag to mark test as failing
Merge pull request #2247 from ConradIrwin/kernel-method-failure

Failing spec for __method__ in class body.