dpkg: Stop exporting DPKG_LIBDIR to maintainer scripts

Now that the maintainer scripts helper program is under PATH, there's
no need anymore to export the internal dpkg library directory.

debian/changelog

@@ -82,6 +82,7 @@ dpkg (1.15.8) UNRELEASED; urgency=low
     on “dpkg-query --list”, so that it does not get incorrectly trimmed.
   * Consistently use earlier/later instead of smaller/bigger when describing
     comparison relationships. Closes: #587641
+  * Stop exporting DPKG_LIBDIR to maintainer scripts, no need for it anymore.
 
   [ Updated programs translations ]
   * Catalan (Guillem Jover).

lib/dpkg/dpkg.h

@@ -81,7 +81,6 @@ DPKG_BEGIN_DECLS
 #define MAINTSCRIPTPKGENVVAR "DPKG_MAINTSCRIPT_PACKAGE"
 #define MAINTSCRIPTARCHENVVAR "DPKG_MAINTSCRIPT_ARCH"
 #define MAINTSCRIPTNAMEENVVAR "DPKG_MAINTSCRIPT_NAME"
-#define MAINTSCRIPTLIBDIRENVVAR "DPKG_LIBDIR"
 #define MAINTSCRIPTDPKGENVVAR "DPKG_RUNNING_VERSION"
 
 #define SHELLENV            "SHELL"

man/dpkg.1

@@ -690,10 +690,6 @@ examine the situation. Contains the path to the new conffile.
 Defined by \fBdpkg\fP on the maintainer script environment to the
 version of the currently running \fBdpkg\fP instance.
 .TP
-.B DPKG_LIBDIR
-Defined by \fBdpkg\fP on the maintainer script environment to the
-private library directory of the currently running \fBdpkg\fP instance.
-.TP
 .B DPKG_MAINTSCRIPT_PACKAGE
 Defined by \fBdpkg\fP on the maintainer script environment to the
 package name being handled.

src/Makefile.am

@@ -6,7 +6,6 @@ pkgconfdir = $(sysconfdir)/@PACKAGE@
 AM_CPPFLAGS = \
 	-DLOCALEDIR=\"$(localedir)\" \
 	-DADMINDIR=\"$(admindir)\" \
-	-DPKGLIBDIR=\"$(pkglibdir)\" \
 	-idirafter $(top_srcdir)/lib/compat \
 	-I$(top_builddir) \
 	-I$(top_srcdir)/lib

src/help.c

@@ -261,7 +261,6 @@ do_script(struct pkginfo *pkg, struct pkginfoperfile *pif,
     if (setenv(MAINTSCRIPTPKGENVVAR, pkg->name, 1) ||
         setenv(MAINTSCRIPTARCHENVVAR, pif->architecture, 1) ||
         setenv(MAINTSCRIPTNAMEENVVAR, cmd->argv[0], 1) ||
-        setenv(MAINTSCRIPTLIBDIRENVVAR, PKGLIBDIR, 1) ||
         setenv(MAINTSCRIPTDPKGENVVAR, PACKAGE_VERSION, 1))
       ohshite(_("unable to setenv for maintainer script"));