[Bug bootstrap/107869] garbled output from configure for darwin and bsd

[redi at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107869

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
There's another similar case in libstdc++-v3/configure:

checking whether to build libbacktrace support... checking for sys/mman.h...
(cached) yes
yes