proc: limit iteration depth of (*G).UserCurrent (#2135)
proc: limit iteration depth of (*G).UserCurrent (#2135)

Limit the iteration depth of proc.(*G).UserCurrent so that it doesn't
keep going forever if the stack trace is not valid.

Fixes #2119
go-delve/delve,go-delve/delve,aarzilli/delve,go-delve/delve,aarzilli/delve,aarzilli/delve,aarzilli/delve,go-delve/delve,go-delve/delve