misc debugging

• -d:useNodeIds
• -d:nimVMDebug (VM)
• -d:debug => this forces a stacktrace for nim built w --stacktrace on; note: maybe this shd be enabled via isDefined("debug") ?
• conditionally control compiler from compiled code: see https://github.com/nim-lang/Nim/pull/14443#issuecomment-633322106 using {.define(enableMyDebug).}

lldb

(lldb) disas
t10916`NimMainModule:
b NimMainModule

dtrace