which directory (typically) contains `include` and `lib` subdirectories.
No ending slash or backslash is necessary.
+## Dependency options (Apple frameworks)
+
+- `COREFOUNDATION_FRAMEWORK`: Absolute path to `CoreFoundation` framework. (for IPv6 non-c-ares, SecTrust, wolfSSL)
+- `CORESERVICES_FRAMEWORK`: Absolute path to `CoreServices` framework. (for IPv6 non-c-ares, SecTrust)
+- `FOUNDATION_FRAMEWORK`: Absolute path to `Foundation` framework. (for Rustls)
+- `SECURITY_FRAMEWORK`: Absolute path to `Security` framework. (for Rustls, SecTrust, wolfSSL)
+- `SYSTEMCONFIGURATION_FRAMEWORK`: Absolute path to `SystemConfiguration` framework. (for IPv6 non-c-ares)
+
## Test tools
- `APXS`: Default: `apxs`