Update builtin function documentation.

	* doc/extend.exi: Add "free" to list of other builtin functions
	supported by GCC.

gcc/ChangeLog

+2020-04-22  Zackery Spytz  <zspytz@gmail.com>
+
+	* doc/extend.exi: Add "free" to list of other builtin functions
+	supported by GCC.
+
 2020-04-20  Aaron Sawdey  <acsawdey@linux.ibm.com>
 
 	PR target/94622

gcc/doc/extend.texi

@@ -12315,6 +12315,7 @@ is called and the @var{flag} argument passed to it.
 @findex fprintf_unlocked
 @findex fputs
 @findex fputs_unlocked
+@findex free
 @findex frexp
 @findex frexpf
 @findex frexpl