https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116362
--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> --- It's hardcoded for newlib here: https://gcc.gnu.org/git/?p=gcc.git;a=blob;f=libstdc%2B%2B-v3/configure.ac;h=ccb24a82be7993da5468ade43b03c01b6142a25f;hb=HEAD#l379