Check for STDC_NO_ATOMICS

[embhorn]

Description

The code checks for C11, then tries to include stdatomic.h, but MSVC does have this header (its an optional C11 feature). MSVC does #define __STDC_NO_ATOMICS__, which could be used

Fixes zd# 20088

Testing

Customer confirmed

Checklist

• [ ] added tests
• [ ] updated/added doxygen
• [ ] updated appropriate READMEs
• [ ] Updated manual and documentation