fix PR 15726: ptrdiff_t should be int on PowerPC Darwin

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@182029 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Basic/Targets.cpp b/lib/Basic/Targets.cpp
index 6b376b3..0086f05 100644
--- a/lib/Basic/Targets.cpp
+++ b/lib/Basic/Targets.cpp
@@ -1220,6 +1220,7 @@
     : DarwinTargetInfo<PPC32TargetInfo>(triple) {
     HasAlignMac68kSupport = true;
     BoolWidth = BoolAlign = 32; //XXX support -mone-byte-bool?
+    PtrDiffType = SignedInt;	// for http://llvm.org/bugs/show_bug.cgi?id=15726
     LongLongAlign = 32;
     SuitableAlign = 128;
     DescriptionString = "E-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-"