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/lib/DtSvc/Makefile.am

@@ -6,7 +6,7 @@ libDtSvc_la_LDFLAGS = -version-info 2:1:0
 
 # USe CPPFLAGS so it will apply to both C and C++ components
 libDtSvc_la_CPPFLAGS = -I./include -DMULTIBYTE -DNLS16 -I../include \
-	@DT_INCDIR@ -DCDE_INSTALLATION_TOP=\"${prefix}\" \
+	@DT_INCDIR@ -DCDE_INSTALLATION_TOP=\"$(CDE_INSTALLATION_TOP)\" \
        -DCDE_CONFIGURATION_TOP=\"$(CDE_CONFIGURATION_TOP)\"
 
 if SOLARIS