enable compiling without XSPICE on specific OSs

src/Makefile.am

@@ -167,7 +167,7 @@ ngspice_LDADD += \
 	xspice/ipc/libipcxsp.la \
 	xspice/idn/libidnxsp.la 
 endif
-ngspice_LDADD += @XSPICEDLLIBS@
+ngspice_LDADD += $(XSPICEDLLIBS)
 
 ngspice_LDADD += \
 	frontend/parser/libparser.la \
@@ -453,7 +453,7 @@ libspice_la_LIBADD += \
 	xspice/ipc/libipcxsp.la \
 	xspice/idn/libidnxsp.la 
 endif
-libspice_la_LIBADD += @XSPICEDLLIBS@
+libspice_la_LIBADD += $(XSPICEDLLIBS)
 
 libspice_la_LIBADD += \
 	frontend/parser/libparser.la \
@@ -577,7 +577,7 @@ libngspice_la_LIBADD += \
 	xspice/ipc/libipcxsp.la \
 	xspice/idn/libidnxsp.la 
 endif
-libngspice_la_LIBADD += @XSPICEDLLIBS@
+libngspice_la_LIBADD += $(XSPICEDLLIBS)
 
 libngspice_la_LIBADD += \
 	frontend/parser/libparser.la \

src/osdi/Makefile.am

@@ -18,7 +18,7 @@ libosdi_la_SOURCES =	\
 	osdicallbacks.c
 
 
-
+libosdi_la_LIBADD = $(XSPICEDLLIBS)
 
 AM_CPPFLAGS = @AM_CPPFLAGS@ -I$(top_srcdir)/src/include
 AM_CFLAGS = $(STATIC)