Remove obsolete AS_SCRUB_INCLUDES macro.

This was an ugly work-around for a bogus warning from gcc-3, a
long-superceded compiler. The way the macro was written caused
portablility issues (see PR 102) and other projects (gstreamer
in particular) removed it several years ago.

Thanks to Julian Ospald for bringing it to our attention.

configure.ac

@@ -555,7 +555,6 @@ fi
 
 LIBXML2_REQUIRED=2.5.10
 PKG_CHECK_MODULES(LIBXML2, libxml-2.0 >= $LIBXML2_REQUIRED)
-AS_SCRUB_INCLUDE(LIBXML2_CFLAGS)
 AC_SUBST(LIBXML2_CFLAGS)
 AC_SUBST(LIBXML2_LIBS)
 
@@ -572,7 +571,6 @@ LIBS="$oLIBS"
 ### LIBXSLT
 
 PKG_CHECK_MODULES(LIBXSLT, libxslt)
-AS_SCRUB_INCLUDE(LIBXLT_CFLAGS)
 AC_SUBST(LIBXSLT_CFLAGS)
 AC_SUBST(LIBXSLT_LIBS)
 
@@ -870,7 +868,6 @@ then
     AQBANKING_LIBS="${AQBANKING_LIBS} -lktoblzcheck"
   fi
 
-  AS_SCRUB_INCLUDE(AQBANKING_CFLAGS)
   AC_SUBST(AQBANKING_LIBS)
   AC_SUBST(AQBANKING_CFLAGS)
   _COMPONENTS="$_COMPONENTS aqbanking"
@@ -1086,23 +1083,19 @@ then
 
 
   PKG_CHECK_MODULES(GTK, gtk+-2.0 >= 2.24.0)
-  AS_SCRUB_INCLUDE(GTK_CFLAGS)
   AC_SUBST(GTK_CFLAGS)
   AC_SUBST(GTK_LIBS)
 
   PKG_CHECK_MODULES(GNOMECANVAS, libgnomecanvas-2.0)
-  AS_SCRUB_INCLUDE(GNOMECANVAS_CFLAGS)
   AC_SUBST(GNOMECANVAS_CFLAGS)
   AC_SUBST(GNOMECANVAS_LIBS)
 
   PKG_CHECK_MODULES(GDK_PIXBUF, gdk-pixbuf-2.0)
-  AS_SCRUB_INCLUDE(GDK_PIXBUF_CFLAGS)
   AC_SUBST(GDK_PIXBUF_CFLAGS)
   AC_SUBST(GDK_PIXBUF_LIBS)
 
    # checks for goffice
   PKG_CHECK_MODULES(GOFFICE, libgoffice-0.8 >= 0.7.0 libgoffice-0.8 < 0.9.0, [goffice=1], [AC_MSG_ERROR([Cannot find libgoffice >= 0.7.0 and < 0.9.0])])
-  AS_SCRUB_INCLUDE(GOFFICE_CFLAGS)
   AC_SUBST(GOFFICE_CFLAGS)
   AC_SUBST(GOFFICE_LIBS)