* mktemp is insecure as it always creates or uses insecure temporary file.
Switch to mkstemp.

* Get and display the error message when an error occurs while creating the temporary file




git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@191616 91177308-0d34-0410-b5e6-96231b3b80d8