[Darwin, PPC, testsuite] Fix pr89313.c fail.

Darwin defines '__POWERPC__' rather than '__powerpc__' so check for
the upper case version too in order to select the correct register
name.

gcc/testsuite:

2019-09-19  Iain Sandoe  <iain@sandoe.co.uk>

	* gcc.dg/pr89313.c: Test for __POWERPC__ in addition to
	__powerpc__ in register name selection.

From-SVN: r275977

gcc/testsuite/ChangeLog

+2019-09-19  Iain Sandoe  <iain@sandoe.co.uk>
+
+	* gcc.dg/pr89313.c: Test for __POWERPC__ in addition to
+	__powerpc__ in register name selection.
+
 2019-09-19  Richard Henderson  <richard.henderson@linaro.org>
 
 	* gcc.target/aarch64/atomic-op-acq_rel.c: Use -mno-outline-atomics.

gcc/testsuite/gcc.dg/pr89313.c

@@ -8,7 +8,7 @@
 # define REG "r0"
 #elif defined (__i386__)
 # define REG "%eax"
-#elif defined (__powerpc__)
+#elif defined (__powerpc__) || defined (__POWERPC__)
 # define REG "r3"
 #elif defined (__s390__)
 # define REG "0"