environment: add ppc -> ppc64 for aix to detect_cpu

This seems like an oversight, that we'd replace ppc with ppc64 on AIX
for the cpu_family, but not for the specific cpu.

mesonbuild/environment.py

@@ -387,6 +387,10 @@ def detect_cpu(compilers: CompilersDict) -> str:
             trial = 'mips'
         else:
             trial = 'mips64'
+    elif trial == 'ppc':
+        # AIX always returns powerpc, check here for 64-bit
+        if any_compiler_has_define(compilers, '__64BIT__'):
+            trial = 'ppc64'
 
     # Add more quirks here as bugs are reported. Keep in sync with
     # detect_cpu_family() above.

unittests/internaltests.py

@@ -1509,7 +1509,7 @@ class InternalTests(unittest.TestCase):
                     self.assertEqual(actual, expected)
 
         with mock.patch('mesonbuild.environment.any_compiler_has_define', mock.Mock(return_value=True)):
-            for test, expected in [('x86_64', 'i686'), ('aarch64', 'arm')]:
+            for test, expected in [('x86_64', 'i686'), ('aarch64', 'arm'), ('ppc', 'ppc64')]:
                 with self.subTest(test, has_define=True), mock_trial(test):
                     actual = mesonbuild.environment.detect_cpu({})
                     self.assertEqual(actual, expected)