ssl_test_lib: move declaration of query_config

Move from ssl_*2.c to ssl_test_lib.h:
* The declaration of query_config(). Also document it.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

programs/ssl/ssl_test_lib.h

@@ -83,6 +83,19 @@
 
 #include <test/helpers.h>
 
+/** Check whether a given configuration symbol is enabled.
+ *
+ * \param config    The symbol to query (e.g. "MBEDTLS_RSA_C").
+ * \return          \c 0 if the symbol was defined at compile time
+ *                  (in MBEDTLS_CONFIG_FILE or config.h),
+ *                  \c 1 otherwise.
+ *
+ * \note            This function is defined in `programs/test/query_config.c`
+ *                  which is automatically generated by
+ *                  `scripts/generate_query_config.pl`.
+ */
+int query_config( const char *config );
+
 #endif /* MBEDTLS_SSL_TEST_IMPOSSIBLE conditions: else */
 
 #endif /* MBEDTLS_PROGRAMS_SSL_SSL_TEST_LIB_H */