Make the PKCS#11 padding string trimming public, add null terminator

src/libstrongswan/plugins/pkcs11/pkcs11_library.h

@@ -55,6 +55,14 @@ struct pkcs11_library_t {
  */
 extern enum_name_t *ck_rv_names;
 
+/**
+ * Trim/null terminate a string returned by the varius PKCS#11 functions.
+ *
+ * @param str		string to trim
+ * @param len		max length of the string
+ */
+void pkcs11_library_trim(char *str, int len);
+
 /**
  * Create a pkcs11_library instance.
  *