Fix erroneous uses of ${prefix} rather than $(CDE_INSTALLATION_TOP)

Some Makefiles use prefix when they should be using
CDE_INSTALLATION_TOP.

Patch by Peter G.

cde/programs/dtwm/Makefile.am

@@ -9,7 +9,7 @@ BUILT_SOURCES = sys.dtwmrc Dtwm.defs
 CLEANFILES = sys.dtwmrc Dtwm.defs
 
 AM_CPPFLAGS = -DLARGECURSORS -DR2_COMPAT -DOPAQUE -DSHAPE -DUNMAP_ON_RESTART \
-	      -DBATCH_DRAG_REQUESTS -DCDE_INSTALLATION_TOP=\"${prefix}\" \
+	      -DBATCH_DRAG_REQUESTS -DCDE_INSTALLATION_TOP=\"$(CDE_INSTALLATION_TOP)\" \
 	      -DCDE_CONFIGURATION_TOP=\"$(CDE_CONFIGURATION_TOP)\"
 
 dtwm_LDADD = $(DTCLIENTLIBS) -lXext $(XTOOLLIB)
@@ -40,7 +40,7 @@ dtwm_SOURCES = WmCDInfo.c      WmCDecor.c      WmCEvent.c \
 
 dtfplist_SOURCES = Print.c Parse.c DataBaseLoad.c WmParse.c Session.c
 
-SCRIPTFLAGS = -DCDE_INSTALLATION_TOP=${prefix} \
+SCRIPTFLAGS = -DCDE_INSTALLATION_TOP=$(CDE_INSTALLATION_TOP) \
               -DCDE_CONFIGURATION_TOP=$(CDE_CONFIGURATION_TOP)
 
 Dtwm.defs: Dtwm.defs.src