Fix MSVC build

Added _WIN32 guards to new platform features. Using correct SetErrorStringWithFormat within Host when LLDB_DISABLE_POSIX is defined. Also fixed an if defined block.

llvm-svn: 195766
diff --git a/lldb/source/Host/common/File.cpp b/lldb/source/Host/common/File.cpp
index 91fc8bd..bbd1185 100644
--- a/lldb/source/Host/common/File.cpp
+++ b/lldb/source/Host/common/File.cpp
@@ -237,8 +237,10 @@
     {
         oflag |= O_RDONLY;
 
+#ifndef _WIN32
         if (options & eOpenoptionDontFollowSymlinks)
             oflag |= O_NOFOLLOW;
+#endif
     }
     
 #ifndef _WIN32