perlapi: Move apidoc lines to proper place

Where they were made autodoc.pl think they were from a new entry

Author: khwilliamson

intrpvar.h

@@ -375,15 +375,15 @@ Set by the L<perlfunc/exit> operator.
 
 =back
 
+On threaded perls, each thread has an independent copy of this variable;
+each initialized at creation time with the current value of the creating
+thread's copy.
+
 =for apidoc Amnh||PERL_EXIT_EXPECTED
 =for apidoc Amnh||PERL_EXIT_ABORT
 =for apidoc Amnh||PERL_EXIT_DESTRUCT_END
 =for apidoc Amnh||PERL_EXIT_WARN
 
-On threaded perls, each thread has an independent copy of this variable;
-each initialized at creation time with the current value of the creating
-thread's copy.
-
 =cut
 */