Merge branch 'cf/c23-const-preserving-strchr-updates-0'

ISO C23 redefines strchr and friends that tradiotionally took a const pointer and returned a non-const pointer derived from it to preserve constness (i.e., if you ask for a substring in a const string, you get a const pointer to the substring). Update code paths that used non-const pointer to receive their results that did not have to be non-const to adjust. * cf/c23-const-preserving-strchr-updates-0: gpg-interface: remove an unnecessary NULL initialization global: constify some pointers that are not written to