TargetLoweringBase: Followup to r321035

I missed some prefixes and the fact that on AArch64 we use "bzero"
instead of "__bzero" as on X86 when doing my refactoring in r321035.

Improve tests for bzero.

llvm-svn: 321046
diff --git a/llvm/lib/CodeGen/TargetLoweringBase.cpp b/llvm/lib/CodeGen/TargetLoweringBase.cpp
index 8a3e679..bef64a5 100644
--- a/llvm/lib/CodeGen/TargetLoweringBase.cpp
+++ b/llvm/lib/CodeGen/TargetLoweringBase.cpp
@@ -130,8 +130,9 @@
     setLibcallName(RTLIB::FPROUND_F32_F16, "__truncsfhf2");
 
     // Darwin 10 and higher has an optimized __bzero.
-    if (!TT.isMacOSX() || !TT.isMacOSXVersionLT(10, 6) || TT.isArch64Bit())
-      setLibcallName(RTLIB::BZERO, "__bzero");
+    if (!TT.isMacOSX() || !TT.isMacOSXVersionLT(10, 6) || TT.isArch64Bit()) {
+      setLibcallName(RTLIB::BZERO, TT.isAArch64() ? "bzero" : "__bzero");
+    }
 
     if (darwinHasSinCos(TT)) {
       setLibcallName(RTLIB::SINCOS_STRET_F32, "__sincosf_stret");