master: false positive in configure for C11 _Static_assert with GCC 4.4.7

[benmenadue]

Thank you for taking the time to submit an issue!

Background information

What version of Open MPI are you using? (e.g., v1.10.3, v2.1.0, git branch name and hash, etc.)

master@385d91b

Describe how Open MPI was installed (e.g., from a source/distribution tarball, from a git clone, from an operating system distribution package, etc.)

git clone

Please describe the system on which you are running

• Operating system/version: CentOS 6.9 + custom kernel (based on CentOS 7.4 kernel)
• Computer hardware: Fujitsu PRIMERGY
• Network type: Mellanox InfiniBand FDR

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Details of the problem

This test erroneously concludes that adding the -c11 flag makes the compiler support _Static_assert. GCC is producing a warning about the unrecognised option, but still successfully compiles the file because it treats _Static_assert(...) as a implicitly-defined function. If it were to try linking the file it would probably fail with an undefined symbol.

configure:15649: checking if gcc -c11 supports C11 _Static_assert
configure:15665: gcc -c -DNDEBUG -g -march=native -c11  conftest.c >&5
gcc: unrecognized option '-c11'
configure:15665: $? = 0
configure:15680: result: yes

This is using

> gcc --version
gcc (GCC) 4.4.7 20120313 (Red Hat 4.4.7-18)
Copyright (C) 2010 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

[jsquyres]

Fixed by #5191.