While reviewing some Gentoo multilib work, I stumbled upon the need to set LIBGCRYPT_CONFIG so that configure script would pick the correct libgcrypt-config when building (in libsecret here, but applies elsewhere as well).
Some search lead me to [[ https://github.com/gpg/libgcrypt/commit/1e8b86494cf8fa045696bd447b16267ffd1797f0 | libgcrypt commit 1e8b86494cf8fa045696bd447b16267ffd1797f0 ]] which changed from AC_PATH_TOOL, which would work fine in this context, to AC_PATH_PROG, which does not.
I understand this is related to SYSROOT support and I have no patch to offer at the moment, I just need a pointer for our teams so we can eventually provide a fix.