using cc executable to detect default compiler in Linux

[memsharded]

Changelog: Fix: Use cc executable in Linux systems for autodetect compiler (conan profile detect and detect_api).
Docs: Omit

Close #8866

Note that this has some risk of breaking autodetection for users that define a weird, unrelated cc executable in their system

[jcar87]

I'd say this is more aligned with the current convention - if I'm not mistaken the cc command used to be specified by POSIX as the interface to the systems' C compiler. Now superseded by the c99 command, but cc is still assumed by longstanding convention.

However, almost all relevant tools (e.g. CMake and Autotools) will consider cc and c++ as the default compilers - this PR aligns better: it should still detect gcc on the vast majority of systems, and if cc or c++ point to something else, it will now be correct.