[AIX][PowerPC] Define __powerpc and __PPC macros

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This patch defines the macros __powerpc and __PPC on AIX to be consistent with XL for AIX. See: https://www.ibm.com/docs/en/xl-c-and-cpp-aix/13.1.0?topic=macros-related-platform

Note: GCC does not currently define __powerpc and __PPC so users should prefer the __powerpc__ and __PPC__ forms.
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Reviewed By: cebowleratibm

Differential Revision: https://reviews.llvm.org/D108917

Author: jakeegan

clang/lib/Basic/Targets/PPC.cpp

@@ -264,6 +264,9 @@ void PPCTargetInfo::getTargetDefines(const LangOptions &Opts,
   }
   if (getTriple().isOSAIX()) {
     Builder.defineMacro("__THW_PPC__");
+    // Define __PPC and __powerpc for AIX XL C/C++ compatibility
+    Builder.defineMacro("__PPC");
+    Builder.defineMacro("__powerpc");
   }
 
   // Target properties.

clang/test/Preprocessor/init-ppc.c

@@ -322,6 +322,7 @@
 // PPC:#define __NATURAL_ALIGNMENT__ 1
 // PPC:#define __POINTER_WIDTH__ 32
 // PPC:#define __POWERPC__ 1
+// PPC-NOT:#define __PPC 1
 // PPC:#define __PPC__ 1
 // PPC:#define __PTRDIFF_TYPE__ long int
 // PPC:#define __PTRDIFF_WIDTH__ 32
@@ -386,6 +387,7 @@
 // PPC:#define __WCHAR_WIDTH__ 32
 // PPC:#define __WINT_TYPE__ int
 // PPC:#define __WINT_WIDTH__ 32
+// PPC-NOT:#define __powerpc 1
 // PPC:#define __ppc__ 1
 
 // RUN: %clang_cc1 -E -dM -ffreestanding -triple=powerpc-ibm-aix7.1.0.0 -fno-signed-char < /dev/null | FileCheck -match-full-lines -check-prefix PPC-AIX %s
@@ -520,6 +522,7 @@
 // PPC-AIX-NOT:#define __NATURAL_ALIGNMENT__ 1
 // PPC-AIX:#define __POINTER_WIDTH__ 32
 // PPC-AIX:#define __POWERPC__ 1
+// PPC-AIX:#define __PPC 1
 // PPC-AIX:#define __PPC__ 1
 // PPC-AIX:#define __PTRDIFF_TYPE__ long int
 // PPC-AIX:#define __PTRDIFF_WIDTH__ 32
@@ -587,6 +590,7 @@
 // PPC-AIX:#define __WCHAR_WIDTH__ 16
 // PPC-AIX:#define __WINT_TYPE__ int
 // PPC-AIX:#define __WINT_WIDTH__ 32
+// PPC-AIX:#define __powerpc 1
 // PPC-AIX:#define __powerpc__ 1
 // PPC-AIX:#define __ppc__ 1