When cross-compiling geckodriver for i686-pc-windows-gnu from Linux
x86-64, this custom cargo configuration is needed. It specifies
the linker to use as well as a rustc flag for disabling backtraces
on panic, as far as I gather.
Neither of these options are necessary, of course, when we start
releasing geckodriver from Taskcluster, because we will then not
rely on cross-compilation.
MozReview-Commit-ID: 6q7wIBNrCHB
--HG--
extra : rebase_source : d71360ab043bf169871de58dfaded1a3281132e3