tools/libs/guest: fix Makefile regarding zlib options

When renaming the libxenguest sources to xg_*.c there was an omission
in the Makefile when setting the zlib related define for the related
sources. Fix that.

Fixes: e3dd624e48 ("tools/libxc: move libxenguest to tools/libs/guest")
Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>

tools/libs/guest/Makefile

@@ -94,8 +94,8 @@ else
 zlib-options = $(ZLIB)
 endif
 
-xc_dom_bzimageloader.o: CFLAGS += $(filter -D%,$(zlib-options))
-xc_dom_bzimageloader.opic: CFLAGS += $(filter -D%,$(zlib-options))
+xg_dom_bzimageloader.o: CFLAGS += $(filter -D%,$(zlib-options))
+xg_dom_bzimageloader.opic: CFLAGS += $(filter -D%,$(zlib-options))
 
 LIBHEADER := xenguest.h