pkg/35952: pkgsrc gets confused by PKG_CONFIG_PATH

[rillig%NetBSD.org@localhost]

>Number:         35952
>Category:       pkg
>Synopsis:       pkgsrc gets confused by PKG_CONFIG_PATH
>Confidential:   no
>Severity:       critical
>Priority:       medium
>Responsible:    pkg-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Mar 08 23:25:00 +0000 2007
>Originator:     Roland Illig
>Release:        
>Organization:
>Environment:
>Description:
When the PKG_CONFIG_PATH variable is set to $LOCALBASE/lib/pkgconfig, all 
installed packages are visible to the pkg-config tool, even if it is wrapped by 
the tool wrapper.

>How-To-Repeat:
cd multimedia/mjpegtools
pkg_add gtk2+
env PKG_CONFIG_PATH=$LOCALBASE/lib/pkgconfig bmake
: "Expect it to fail because of a missing <gtk/gtk.h> header."
bmake clean

env PKG_CONFIG_PATH=/nonexistent bmake
: "This time, it works."

>Fix:
One of:

1) Ignore the value of PKG_CONFIG_PATH altogether by overriding it in 
mk/tools/pkg-config.mk, like PKG_CONFIG_LIBDIR.

2) Document that custom settings of PKG_CONFIG_PATH are not supported.
   Add a check for that.