Put the CopyFile function explicitly in the sys namespace.

llvm-svn: 19079
diff --git a/llvm/lib/System/Unix/Path.cpp b/llvm/lib/System/Unix/Path.cpp
index 3357330..e0ca7df 100644
--- a/llvm/lib/System/Unix/Path.cpp
+++ b/llvm/lib/System/Unix/Path.cpp
@@ -548,7 +548,7 @@
 }
 
 void 
-CopyFile(const sys::Path &Dest, const sys::Path &Src) {
+sys::CopyFile(const sys::Path &Dest, const sys::Path &Src) {
   int inFile = -1;
   int outFile = -1;
   try {