Fix Makefile.in

* Use $(CC) instead of $(CPP) to generate .depend file because
  '$(CPP) -M' call does not support multiple input files.
  This avoid the following error:

make[1]: Entering directory `/opt/br/output/build/newt-0.51.0'
/opt/br/output/host/usr/bin/arm-none-linux-gnueabi-cpp -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -D_GNU_SOURCE -M newt.c button.c form.c checkbox.c entry.c label.c listbox.c scrollbar.c textbox.c scale.c grid.c windows.c buttonbar.c checkboxtree.c > .depend
arm-none-linux-gnueabi-cpp: too many input files
make[1]: *** [depend] Error 1
make[1]: Leaving directory 
`/opt/br/output/build/newt-0.51.0'
make: *** 
[/opt/br/output/build/newt-0.51.0/.stamp_built] Error 2

Signed-off-by: Samuel Martin <s.martin49@gmail.com>
Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com>

---
 Makefile.in |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Index: b/Makefile.in
===================================================================
--- a/Makefile.in
+++ b/Makefile.in
@@ -121,7 +121,7 @@
 		$(SHAREDDIR)/*.o *.$(SOEXT)*
 
 depend:
-	$(CPP) $(CFLAGS) $(CPPFLAGS) -M $(SOURCES) > .depend
+	$(CC) $(CFLAGS) $(CPPFLAGS) -M $(SOURCES) > .depend
 
 $(SHAREDDIR):
 	mkdir -p $(SHAREDDIR)
