Function llvm_sys::core::LLVMAddModuleFlag

pub unsafe extern "C" fn LLVMAddModuleFlag(
    M: LLVMModuleRef, 
    Behavior: LLVMModuleFlagBehavior, 
    Key: *const c_char, 
    KeyLen: size_t, 
    Val: LLVMMetadataRef
)

Add a module-level flag to the module-level flags metadata if it doesn't already exist.