arm: testuite: Missing optimization pattern for rev16 with thumb1

This patch marks a rev16 test as XFAIL for architectures having only
Thumb1 support.  The generated code is functionally correct, but the
optimization is disabled when -mthumb is equivalent to Thumb1.  Fixing
the root issue would requires changes that are not suitable for GCC14
stage 4.  More information at
https://linaro.atlassian.net/browse/GNU-1141

gcc/testsuite/ChangeLog:

	* gcc.target/arm/rev16_2.c: XFAIL when compiled with Thumb1.

gcc/testsuite/gcc.target/arm/rev16_2.c

@@ -17,4 +17,4 @@ __rev16_32 (__u32 x)
          | (((__u32)(x) & (__u32)0xff00ff00UL) >> 8);
 }
 
-/* { dg-final { scan-assembler-times {rev16\tr[0-9]+, r[0-9]+} 2 } } */
+/* { dg-final { scan-assembler-times {rev16\tr[0-9]+, r[0-9]+} 2 { xfail arm_thumb1_ok } } } */
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