Add compiler language flags in build.h header [ci skip]
Add compiler language flags in build.h header [ci skip]

Fixes #1353

randombit/botan,Rohde-Schwarz-Cybersecurity/botan,webmaster128/botan,randombit/botan,webmaster128/botan,randombit/botan,Rohde-Schwarz-Cybersecurity/botan,randombit/botan,Rohde-Schwarz-Cybersecurity/botan,webmaster128/botan,webmaster128/botan,randombit/botan,Rohde-Schwarz-Cybersecurity/botan,webmaster128/botan,Rohde-Schwarz-Cybersecurity/botan,Rohde-Schwarz-Cybersecurity/botan