Bug #120194.
Add Autotools plumbing for FTL JIT enabling.
Add Automake plumbing for FTL JIT support - adding files to the build and using LLVM cflags and libs as necessary.
Add 'automatical' FTL JIT enabling for the GTK port on supported architectures.
Check for llvm-config, gather its version and check that it's at least 3.4.
Add LLVMDisassembler, X86Disassemler source files to the build.
Fix llvm-config version extraction and comparison.
Add <cstring> inclusion in FTLAbbreviations header for using std::strlen.