cicd: gcc_coverage image has problems with non-standard extensions and segfaults

From a certain downstream project:

Even though we use strict ISO C and C++ with POSIX somehow the CICD job for coverage links to stdlib with extensions. This is a bug, since functions from our ISO+POSIX compliant application get overridden by some extension.

Not only is there function clashing, this actually called a proper test to segfault on MR...

Either a bug in Alpine's testing distribution or caused due to musl libc not working nicely with GCC's coverage.