testsuite: Prune warning about size of enums

This fixes reported regression at
https://linaro.atlassian.net/browse/GNU-1315

.

gcc/testsuite/ChangeLog:

	* g++.dg/warn/pr33738-2.C: dg-prune arm linker messages about
	size of enums.

Signed-off-by: Torbjörn SVENSSON <torbjorn.svensson@foss.st.com>

gcc/testsuite/g++.dg/warn/pr33738-2.C

 // { dg-do run }
+// { dg-prune-output "use of enum values across objects may fail" }
 // { dg-options "-O2 -Wtype-limits -fstrict-enums -fshort-enums" }
 extern void link_error (void);