configure script ELF visibility

[Frank]

Hi,

can someone explain the configure script to me?
I am still looking for a way to make my libgpg-error and libassuan  
(see gnupg2 vs gnupg) work with the 'darn' IBM dnf compilation.
And I am currently eyeing at the 'ELF visibility' check in the  
configure script.
I do not understand, what or how it intends to test.
I cannot find confdefs.h or conftest.* to see what a manual compile  
would result in.
According to IBMs Webpage xlC/C++ supports visibility.
https://www.ibm.com/docs/en/xl-c-and-cpp-aix/16.1?topic=performance-using-visibility-attributes-extension

Maybe it should be looking like this?
if ${CC-cc} -Werror -qvisibility -S conftest.c -o conftest.s \

If my amateurish tries are correct the grep would look (maybe) different:
.globl  foo{RW},hidden
.globl  bar{RW},protected

Though I noticed earlier that the -Werror seems to be not supported with
cc, xlc, xlC, xlc++ they only support -qhalt={i,w,e,s}
only xlclang++ seems to support it.
see  
https://www.ibm.com/docs/cs/xl-c-and-cpp-aix/16.1?topic=descriptions-qhalt-werror

If I am on the wrong path, just tell me.

Kind regards
Frank