First commit for TalesPH2Bitcode/TalesClang.

Modified Clang driver that preserves all class/struct/union declarations
in a specified file or folder (the PH bits are next). LLVM and Clang
needed a number of changes to make that possible, and the build system
rests upon a bash script in order to patch a LLVM source tree. Although
this breaks once more VS compatibility, it's much more convenient for
Unix environments.

TalesClang replaces Clang for the IR generation of TalesRuntime.c, which
means the workarounds telling Clang to keep some types aren't needed any
longer.

And finally Tales doesn't require a LLVM system install anymore, which
can save many gigabytes and time.