Fix copy-paste defect in comment.
Commit introduced it.
* GCC: https://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html
* GCC: https://gcc.gnu.org/onlinedocs/gcc/Type-Attributes.html
* Sunpro: https://docs.oracle.com/cd/E18659_01/html/821-1384/gjzke.html
- * XLC: https://www.ibm.com/support/knowledgecenter/SSGH2K_13.1.2/com.ibm.xlc131.aix.doc/language_ref/type_attrib.html
+ * XLC: https://www.ibm.com/support/knowledgecenter/SSGH2K_13.1.2/com.ibm.xlc131.aix.doc/language_ref/function_attributes.html
* XLC: https://www.ibm.com/support/knowledgecenter/SSGH2K_13.1.2/com.ibm.xlc131.aix.doc/language_ref/type_attrib.html
*/
