Make -Wl,-headerpad_max_install_names a default compiler flag

[jacknagel]

Since we use install_name_tool liberally, we should be using this flag by default. This would resolve some issues that happen from time to time (we may seem similar issues when we start bottling more stuff).

It's trivial to add it to stdenv, but to add it to superenv we need to be able to use -Wl,-headerpad_max_install_names when the cc wrapper is invoked in :cc and :ccld mode and just -headerpad_max_install_names when invoked in :ld mode.

[MikeMcQuaid]

Good idea/points.

[cooljeanius]

For reference, MacPorts started doing this in trunk as of their r104258

[samueljohn]

+1

[jacknagel]

Okay, I tried adding this to superenv: https://github.com/jacknagel/homebrew/compare/headerpad

I don't like the conditional and I'm not confident that it won't break, but the idea is that when the wrapper is in :ld mode, we omit the leading -Wl, (which would make the linker choke).

I see that I stated earlier that it would be "trivial" to add to stdenv, but of course I don't remember why. Perhaps we can just add -Wl,-headerpad_max_install_names to CFLAGS and -headerpad_max_install_names to LDFLAGS.

/cc @adamv @mistydemeo

[jacknagel]

Okay, both gentoo and macports treat LDFLAGS as suitable for passing to cc rather than directly to ld, so going with that in stdenv for now.

[mistydemeo]

Sounds good to me. From what I can see this is supported back to 10.4 (though at least at one point it was 32-bit only), so no compatibility issues to worry about.