Fix test failures for enum-alias-{1,2,3} on arm-eabi [PR117419]

The tests added for PR115157 fail on arm-eabi.  Add __INT_MAX__
to enum to make sure they have size int.

	PR testsuite/117419

gcc/testsuite/ChangeLog:
	* gcc.dg/enum-alias-1.c: Add __INT_MAX__.
	* gcc.dg/enum-alias-2.c: Likewise.
	* gcc.dg/enum-alias-3.c: Likewise.

Tested-by: Thiago Jung Bauermann <thiago.bauermann@linaro.org>