[Bug lto/66014] 5.1 mingw64 fails to perform slim bootstrap-lto: ccEt8YNj.ltrans4.ltrans.o:<artificial>:(.text+0x628): undefined reference to `stpcpy'

[breedlove.matt at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66014

--- Comment #1 from Matt Breedlove <breedlove.matt at gmail dot com> ---
This issue is still present on 5.1.0 and trunk.  The issue seems to be related
to libiberty's implementation of stpcpy being replaced with the GCC builtin and
then causing linker errors due to that symbol not being defined when attempting
to link lto-plugin.

Passing in -fno-builtin-stpcpy when building libiberty has resolved this for me
and allows the build to progress but I'm unsure if there is any other potential
fallout from similar issues.