Incorrect use of user link flags in bindgen.

Hello,

In generate_cc_link_build_info, the field user_link_flags of the LinkerInput is used to extend the command line of rustc through --arg-file:

rules_rust/bindgen/private/bindgen.bzl

Line 127 in 012af3b

linker_flags.extend(linker_input.user_link_flags)

It doesn't work with platform-specific linker flags such as Apple's -framework.

Here is a PoC:

# BUILD
load("@rules_rust//bindgen:defs.bzl", "rust_bindgen_library")                    
                                                                                 
cc_library(                                                                      
    name = "foo",                                                                
    srcs = ["foo.c"],                                                            
    hdrs = ["foo.h"],                                                            
    linkopts = ["-framework", "Security"],                                       
)                                                                                
                                                                                 
rust_bindgen_library(                                                            
    name = "foo_bindgen",                                                        
    cc_lib = ":foo",                                                             
    header = "foo.h",                                                            
)

Bazel fails with the following error:

error: Unrecognized option: 'f'

The content of the .link_flags is the following:

-lstatic=foo
-framework
Security

-framework is treated as -f ramework, leading to the Unrecognized option error.

Since user_link_flags is supposed to contain linker flags, I think you should instead use the codegen option link-args:

-C
link-args=-framework Security

(Note that -lstatic= arguments won't end up in link-args since they don't come from user_link_flags)

[UebelAndre]

That sounds reasonable. Happy to review a PR 😄