plug-ins: port warp to GEGL, stupid 8-bit port only

And put it back in the menus, it's just too weird not to have.

plug-ins/common/Makefile.am

@@ -1562,6 +1562,7 @@ warp_LDADD = \
 	$(libgimpcolor)		\
 	$(libgimpbase)		\
 	$(GTK_LIBS)		\
+	$(GEGL_LIBS)		\
 	$(RT_LIBS)		\
 	$(INTLLIBS)		\
 	$(warp_RC)

plug-ins/common/plugin-defs.pl

@@ -73,7 +73,7 @@
     'tile-small' => { ui => 1, gegl => 1 },
     'unit-editor' => { ui => 1 },
     'van-gogh-lic' => { ui => 1, gegl => 1 },
-    'warp' => { ui => 1 },
+    'warp' => { ui => 1, gegl => 1 },
     'wavelet-decompose' => { ui => 1, gegl => 1 },
     'web-browser' => { ui => 1, ldflags => '$(framework_cocoa)', cppflags => '$(AM_CPPFLAGS) $(xobjective_c)' },
     'web-page' => { ui => 1, optional => 1, libs => 'WEBKIT_LIBS', cflags => 'WEBKIT_CFLAGS' }