forward linker option to lint-docs This fixes an error found when building the doc for a cross-built toolchain. ``` warning: the code example in lint `unstable_syntax_pre_expansion` in /buildroots/chenx97/rustc-1.80.1-src/compiler/rustc_lint_defs/src/builtin.rs failed to generate the expected output: did not find lint `unstable_syntax_p re_expansion` in output of example, got: error: linking with `cc` failed: exit status: 1 ... ``` Closes: #129956