Fix NSEdoc generation problem

@field tag names in NSEdoc must be valid identifiers, so they cannot
contain "-". As a general rule, anything that needs to be quoted like
this: mytable["field-name"] is invalid. In this case, the ajp library
had a field called "status-line", which caused NSEdoc generation to fail
when it was finally documented. This change renames it to "status_line",
which should fix the issue.