exp2* tests: More tests. * tests/test-exp2.h (test_function): Test all integral arguments that don't need to overflow or denormalized numbers. * tests/test-exp2.c (MAX_EXP, MIN_EXP): New macros. * tests/test-exp2f.c (MAX_EXP, MIN_EXP): Likewise. * tests/test-exp2l.c (MAX_EXP, MIN_EXP): Likewise.