Fix yesterday's patch so that it also works for the last flag.
Still part of the fix for bug#40546.

support-files/mysql.spec.sh:
  The original "sed" command relied on a blank following the flag
  which should be removed for debug builds.
  This meant the last flag would not be matched.
  Change it so that the whole string is enclosed in blanks,
  demand leading and trailing blank for each flag,
  and finally strip the leading + trailing blank.