Cleaned up charset inlines in internal.h, with new charset_complement() and charset_restrict_to_range() support

LLVM backend

ch_llvm JITs successfully, but its call to h_read_bits crashes; the HInputStream seems to be invalidated

Fix most of ch_llvm()

fixing LLVM function declarations; turns out repeat calls to LLVMPointerType(...) create shadow declarations

LLVM backend