Minor safety change, parameter names in macros should be parenthesized,
the only exception is the comma operator.

https://www.securecoding.cert.org/confluence/display/seccode/PRE01-C.+Use+parentheses+within+macros+around+parameter+names
Stop combining "it's a remove operation" and "it's an append of a new
record" into the same flag value, split them apart.
For now, fix the comment to match the code.  Ref #644.