[lldb] Don't emit .lldbinit warning as an error

Actually emit a warning, rather than an error, when there's an .lldbinit
file in the current directly. Currently, the message is prepended by
"error" which looks rather odd, as the warning refer to itself as a
warning.

Author: JDevlieghere

lldb/source/Interpreter/CommandInterpreter.cpp

@@ -2591,7 +2591,7 @@ void CommandInterpreter::SourceInitFileCwd(CommandReturnObject &result) {
         llvm::sys::path::parent_path(home_init_file.GetPath())) {
       result.SetStatus(eReturnStatusSuccessFinishNoResult);
     } else {
-      result.AppendError(InitFileWarning);
+      result.AppendWarning(InitFileWarning);
     }
   }
   }

lldb/test/Shell/Driver/LocalLLDBInit.test

@@ -9,7 +9,7 @@
 # RUN: env HOME=%t.home %lldb-init -local-lldbinit -o 'settings show frame-format' 2>&1 | FileCheck %s --check-prefix=ALLOWINIT --check-prefix=NOINIT
 # RUN: %lldb -o 'settings show frame-format' 2>&1 | FileCheck %s --check-prefix=NOINIT --check-prefix=CHECK
 
-# WARNINIT: There is a .lldbinit file in the current directory which is not being read.
+# WARNINIT: warning: There is a .lldbinit file in the current directory which is not being read.
 # NOINIT-NOT: There is a .lldbinit file in the current directory which is not being read.
 # CHECK-NOT: bogus
 # ALLOWINIT: name 'prlnt' is not defined