The autoconf script for libassuan were fixed in this commit: https://dev.gnupg.org/rAb9b7f1cf3fd0228fd31cb62a144628ee8ad26953
However, this fix wasn't propagated to other projects that carry the assuan m4 (usually in m4/libassuan.m4), resulting in issues when building like:
```
In file included from sysutils.c:32:0:
../config.h:650:33: error: token "$" is not valid in preprocessor expressions
#define LIBASSUAN_API_REQUESTED $req_libassuan_api
^
```
The `AC_DEFINE_UNQUOTED` fix should be added to those projects (and any others I didn't mention).