disable zinks shader cache when the needed functions do not exist
As mentioned in #7519 (closed) zink is currently broken on macos. This should fix the problem i found. The shader cache implementation of zink uses the functions in src/util/build_id.h without checking if HAVE_DL_ITERATE_PHDR is defined. This commit just adds this check and thus disables the cache when these functions are not available.
Closes #7519 (closed).
Edited by noasakurajin