Makefile: Output to explicit target

Don't depend on the C compiler's default output file name and path. Make
knows what it wants to build and where it should go, and this may not
always align with the C compiler default, so tell the C compilter to
output to the Make target explicitly.
diff --git a/library/Makefile b/library/Makefile
index b79bc6b..4238a1c 100644
--- a/library/Makefile
+++ b/library/Makefile
@@ -132,7 +132,7 @@
 
 .c.o:
 	echo "  CC    $<"
-	$(CC) $(LOCAL_CFLAGS) $(CFLAGS) -c $<
+	$(CC) $(LOCAL_CFLAGS) $(CFLAGS) -c $< -o $@
 
 clean:
 ifndef WINDOWS