Log Message:
pkgtools/pkglint: update to 5.7.5

Changes since 5.7.4:

* Warn about invalid variable uses in directives like
  .if and .for

* Do not warn when a package-settable variable is assigned using the ?=
  operator before including bsd.prefs.mk. This warning only makes sense
  for user-settable and system-provided variables.

* The parser for variable uses like ${VAR:@v@${v:Q}} is more robust now,
  which reduces the number of parse errors and leads to more appropriate
  diagnostics, in cases like ${URL:Mftp://*}, which should really be
  ${URL:Mftp\://*}.

* The valid values for OPSYS are now determined by the files in
  mk/platform instead of allowing arbitrary identifiers. This catches a
  few instances where "Solaris" is used instead of the correct \ 
"SunOS".

* Setting USE_LANGUAGES only has an effect if mk/compiler.mk has not yet
  been included. In all other cases, pkglint warns now.

* Missing entries in doc/CHANGES produce a note now. This will lead to
  more accurate statistics for the release notes.