FYI: Fix for gcc PR36312 breaks glibc builds over usage of /dev/null as input and output file.

[Carlos O'Donell]

FYI.

The fix for gcc PR36312 breaks glibc builds.

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=36312

The fix disallows this common configure idiom:

configure:72: checking for AVX support
configure:78: /home/triegel/local/gcc/bin/gcc -mavx -xc /dev/null -S -o /dev/null
gcc: fatal error: input file '/dev/null' is the same as output file
compilation terminated.
configure:81: $? = 1
configure:89: result: no

PR is reopened with a request to fix.

Alternatively we could discuss changing glibc, but I think
this will impact more than just glibc.

Cheers,
Carlos.