Allow passing flags to cc compiler for linking

[xlxs4]

To modify the flags passed to the julia and cc compiler invocations by JuliaC, I'm using it programmatically. To modify the arguments passed to julia I can use julia_args. If I use the JuliaC binary (juliac) I can pass arguments passed to julia using the -- separator. To modify the compile command (both the compiler used and the flags passed to it) I'm using JULIA_CC.

I'd like to be able to decouple specifying the cc compiler from specifying user-supplied flags passed to the compiler, so that I can pass any flags I want while also taking advantage of the auto compiler discovery logic in get_compiler_cmd

# ...
link = LinkRecipe(
    image_recipe = img,
    outname = "libmylib",
    rpath = nothing, # set automatically when bundling
    cc_flags = ["-O2"]
)
# ...

[xlxs4]

This would also simplify my building configuration, because I would be able to pass -soname/-install_name directly during linkage, instead of post-build modifications: https://discourse.julialang.org/t/cmake-configuration-for-working-with-juliac-compiled-libraries/133320

[xlxs4]

This would also simplify my building configuration, because I would be able to pass -soname/-install_name directly during linkage, instead of post-build modifications: https://discourse.julialang.org/t/cmake-configuration-for-working-with-juliac-compiled-libraries/133320

E: #74

[gbaraldi]

these are technically link flags so I would name something like ld_flags. Specially since the image recipe already has flags

[xlxs4]

27839d5

[gbaraldi]

I know cc_flags isn't super well tested but could you add a test to this?

[xlxs4]

Wasn't really sure what to test for, you could also just check the output from --verbose instead