Use the default TID format in curses UI

TIDs are conventionally shown as decimal values on FreeBSD and Linux.
Thus, use the ${thread.id%tid} format string to display the thread ID,
instead of a fixed hex format.

llvm.org/pr19380




git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@205912 91177308-0d34-0410-b5e6-96231b3b80d8