Llvm_analysis

`sig
external verify_module : Llvm.llmodule -> string option
= "llvm_verify_module"
external verify_function : Llvm.llvalue -> bool = "llvm_verify_function"
external assert_valid_module : Llvm.llmodule -> unit
= "llvm_assert_valid_module"
external assert_valid_function : Llvm.llvalue -> unit
= "llvm_assert_valid_function"
external view_function_cfg : Llvm.llvalue -> unit
= "llvm_view_function_cfg"
external view_function_cfg_only : Llvm.llvalue -> unit
= "llvm_view_function_cfg_only"
end`