[MacPorts] #73393: pkgconf always reports incorrect cflags for gnutls

[MacPorts]

#73393: pkgconf always reports incorrect cflags for gnutls
--------------------------+--------------------
  Reporter:  OpenSauce04  |      Owner:  (none)
      Type:  defect       |     Status:  new
  Priority:  Normal       |  Milestone:
 Component:  ports        |    Version:  2.11.6
Resolution:               |   Keywords:
      Port:  pkgconf      |
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Comment (by kaniini):

 No, it is a defect in the way pkgconf is built in MacPorts.

 Most likely /opt/local/include is being treated as a system include path
 because the default system include path calculated by pkgconf's configure
 script is `${prefix}/include` (and the default system library path is
 `${prefix}/lib`).

 The fix for this is to set the paths to match the actual behavior of the
 toolchain.  This is important because pkgconf needs to strip redundant
 paths that are included by the toolchain already to ensure the search path
 is correct for overlay libraries like libbsd.

 Original pkg-config does not filter out system include and library paths
 correctly, which is why it works there.

 MacPorts needs to use `--with-system-libdir` and `--with-system-
 includedir` to align the defaults with the toolchain's search paths.
 `clang -print-search-dirs` and `clang -E -v -xc -` can be used to find the
 library and include search paths respectively.

-- 
Ticket URL: <https://trac.macports.org/ticket/73393#comment:3>
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