[flang] Repair recent Power build bot breakage

Add AIX_WARNING expected warnings to a test that is now producing
new warnings.

Should fix https://lab.llvm.org/buildbot/#/builders/201/builds/2291.

Author: klausler

flang/test/Semantics/kinds04_q10.f90

@@ -1,4 +1,5 @@
-! RUN: %python %S/test_errors.py %s %flang_fc1
+! RUN: not %flang_fc1 %s 2>%t.stderr
+! RUN: FileCheck %s --input-file=%t.stderr --check-prefixes=%if system-aix %{"PORTABILITY","WARNING","ERROR","AIX_WARNING"%} %else %{"PORTABILITY","WARNING","ERROR"%}
 ! C716 If both kind-param and exponent-letter appear, exponent-letter
 ! shall be E. (As an extension we also allow an exponent-letter which matches
 ! the kind-param)
@@ -11,11 +12,13 @@ subroutine s(var)
   real :: realvar3 = 4.0Q6
   !PORTABILITY: Explicit kind parameter together with non-'E' exponent letter is not standard
   real :: realvar4 = 4.0D6_8
+  !AIX_WARNING: underflow on REAL(10) to REAL(8) conversion
   !WARNING: Explicit kind parameter on real constant disagrees with exponent letter 'q'
   real :: realvar5 = 4.0Q6_10
   !PORTABILITY: Explicit kind parameter together with non-'E' exponent letter is not standard
   real :: realvar6 = 4.0Q6_16
   real :: realvar7 = 4.0E6_8
+  !AIX_WARNING: underflow on REAL(10) to REAL(8) conversion
   real :: realvar8 = 4.0E6_10
   real :: realvar9 = 4.0E6_16
   !ERROR: Unsupported REAL(KIND=32)
@@ -29,6 +32,7 @@ subroutine s(var)
   !PORTABILITY: Explicit kind parameter together with non-'E' exponent letter is not standard
   double precision :: doublevar5 = 4.0Q6_16
   double precision :: doublevar6 = 4.0E6_8
+  !AIX_WARNING: underflow on REAL(10) to REAL(8) conversion
   double precision :: doublevar7 = 4.0E6_10
   double precision :: doublevar8 = 4.0E6_16
   !ERROR: Unsupported REAL(KIND=32)