Add a test for the built-in key range

Restricting the built-in key range would be an API break since applications
can hard-code a built-in key value and expect that it won't clash with
anything else. Make it harder to accidentally break the API.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/include/psa/crypto_extra.h b/include/psa/crypto_extra.h
index 4039acf..ea58e87 100644
--- a/include/psa/crypto_extra.h
+++ b/include/psa/crypto_extra.h
@@ -717,7 +717,7 @@
  * #PSA_KEY_ID_VENDOR_MIN and #PSA_KEY_ID_VENDOR_MAX and must not intersect
  * with any other set of implementation-chosen key identifiers.
  *
- * This value is part of the library's ABI since changing it would invalidate
+ * This value is part of the library's API since changing it would invalidate
  * the values of built-in key identifiers in applications.
  */
 #define MBEDTLS_PSA_KEY_ID_BUILTIN_MIN          ((psa_key_id_t) 0x7fff0000)