Target triple OS detection tidyup. NFC

Use Triple::isOS*() helpers where possible.

llvm-svn: 222960
diff --git a/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCAsmInfo.cpp b/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCAsmInfo.cpp
index 893aae3..1be7b48 100644
--- a/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCAsmInfo.cpp
+++ b/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCAsmInfo.cpp
@@ -74,9 +74,7 @@
   AssemblerDialect = 1;           // New-Style mnemonics.
   LCOMMDirectiveAlignmentType = LCOMM::ByteAlignment;
 
-  if (T.getOS() == llvm::Triple::FreeBSD ||
-      (T.getOS() == llvm::Triple::NetBSD && !is64Bit) ||
-      (T.getOS() == llvm::Triple::OpenBSD && !is64Bit))
+  if (T.isOSFreeBSD() || ((T.isOSNetBSD() || T.isOSOpenBSD()) && !is64Bit))
     UseIntegratedAssembler = true;
 }