Fix more functions in Args to use StringRef.

This patch also marks the const char* versions as =delete to prevent
their use.  This has the potential to cause build breakages on some
platforms which I can't compile.  I have tested on Windows, Linux,
and OSX.  Best practices for fixing broken callsites are outlined in
Args.h in a comment above the deleted function declarations.

Eventually we can remove these =delete declarations, but for now they
are important to make sure that all implicit conversions from
const char * are manually audited to make sure that they do not invoke a
conversion from nullptr.

llvm-svn: 281919
diff --git a/lldb/source/API/SBPlatform.cpp b/lldb/source/API/SBPlatform.cpp
index 10b7219..6085cef 100644
--- a/lldb/source/API/SBPlatform.cpp
+++ b/lldb/source/API/SBPlatform.cpp
@@ -251,7 +251,8 @@
   PlatformSP platform_sp(GetSP());
   if (platform_sp && connect_options.GetURL()) {
     Args args;
-    args.AppendArgument(connect_options.GetURL());
+    args.AppendArgument(
+        llvm::StringRef::withNullAsEmpty(connect_options.GetURL()));
     sb_error.ref() = platform_sp->ConnectRemote(args);
   } else {
     sb_error.SetErrorString("invalid platform");