Hi.
This patch fixes a segfault that happens when compiling librsvg (more
specifically its dependency aho-corasick) with rustc_codegen_gcc (bug
112575).
I was not able to create a reproducer for this bug: I'm assuming I
might need to concat all the reproducers together in the same file in
order to be able to reproduce the issue.

I'm also not sure I put the cleanup in the correct location.
Is there any finalizer function for target specific code?

Thanks to fix this issue.