Defect in XSH msync()

[Geoff Clare <yyy@xxxxxxxxxxxxx>]

@ page 827 line 27084 section msync editorial [gwc msync is-shall]

Problem:

Defect code :  1. Error

There is a use of "is" on the msync() page which is left over from
SUSv2 and should have been changed to use "shall".  The same text
in POSIX.1-1996 used "shall".

Action:

Change:

    "Either MS_ASYNC or MS_SYNC is specified, but not both."

to:

    "Either MS_ASYNC or MS_SYNC shall be specified, but not both."