Fixed the 5.0-bugteam MacOSX warnings.

client/mysqldump.c:
  Bug #45286: typecasts
cmd-line-utils/readline/bind.c:
  Bug #45286: use variable of right type
cmd-line-utils/readline/display.c:
  Bug #45286: use variable of right type
dbug/user.r:
  Bug #45286: no warnings in generating man pages
strings/ctype.c:
  Bug #45286: typecasts