gobject-introspection: add libtool library path tweaks to scanner

Hopefully the final tweaks, since they now handle both libtool and non-libtool library references, both in-build and outside-build.

Now works work: gobject-introspection, poppler, gstreamer1-gst-plugins-base, py38-gobject3, gexiv2, and libsoup

Ref: https://trac.macports.org/ticket/61427

gnome/gobject-introspection/Portfile

@@ -5,7 +5,7 @@ PortGroup           active_variants 1.1
 
 name                gobject-introspection
 version             1.60.2
-revision            3
+revision            4
 set branch          [join [lrange [split ${version} .] 0 1] .]
 categories          gnome
 platforms           darwin

gnome/gobject-introspection/files/patch-fix-scanner-in-build-execution.diff

@@ -14,7 +14,7 @@
              args.append('-L.')
 --- giscanner/dumper.py.orig
 +++ giscanner/dumper.py
-@@ -236,8 +236,29 @@
+@@ -236,8 +236,28 @@
 
          args.extend(sources)
 
@@ -24,25 +24,24 @@
 +            self._packages, msvc_syntax=self._compiler.check_is_msvc())
 +        this_L = [lib[len('-L'):] for lib in pkg_config_libs_only_L]
 +
-+        # remove self._options.library_paths entries that are in
-+        # "this_L" already, since those are "system" and will be found
-+        # via the "runtime_path_envvar" setting below
-+        tmp_L = []
-+        for t_L in self._options.library_paths:
-+            if t_L not in this_L:
-+                tmp_L.append (t_L)
-+        self._options.library_paths = tmp_L
++        # uniquely merge pkg_config and options library paths
++        self._options.library_paths = list (set().union (self._options.library_paths,
++                                                         this_L))
++
++        # remove anything in LIBRARY_PATH
++        env_LIBRARY_PATH = os.environ['LIBRARY_PATH'].split(':') if \
++            'LIBRARY_PATH' in os.environ else []
++        self._options.library_paths = [l for l in self._options.library_paths
++                                           if l not in env_LIBRARY_PATH]
 +
 +        if os.name == 'nt':
 +            runtime_path_envvar = ['LIB', 'PATH']
 +        else:
 +            runtime_path_envvar = ['LIBRARY_PATH']
 +        for envvar in runtime_path_envvar:
-+            if envvar in os.environ:
-+                os.environ[envvar] = \
-+                    os.pathsep.join(this_L + [os.environ[envvar]])
-+            else:
-+                os.environ[envvar] = os.pathsep.join(this_L)
++            os.environ[envvar] = os.pathsep.join \
++                (list (set().union (os.environ[envvar].split(':'), this_L))) \
++                    if envvar in os.environ else os.pathsep.join(this_L)
 
          if not self._options.external_library:
              self._compiler.get_internal_link_flags(args,