radix tree test suite: Use vpath to find lib files

Instead of specifying how to build find_bit.o from lib/find_bit.o,
use vpath to tell make where to find find_bit.c.
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Reviewed-by: Rehas Sachdeva <aquannie@gmail.com>

tools/testing/radix-tree/Makefile

@@ -2,7 +2,7 @@
 CFLAGS += -I. -I../../include -g -O2 -Wall -D_LGPL_SOURCE
 LDFLAGS += -lpthread -lurcu
 TARGETS = main
-OFILES = main.o radix-tree.o linux.o test.o tag_check.o find_next_bit.o \
+OFILES = main.o radix-tree.o linux.o test.o tag_check.o find_bit.o \
 	 regression1.o regression2.o regression3.o multiorder.o \
 	 iteration_check.o benchmark.o
 
@@ -18,8 +18,7 @@ main:	$(OFILES)
 clean:
 	$(RM) -f $(TARGETS) *.o radix-tree.c
 
-find_next_bit.o: ../../lib/find_bit.c
-	$(CC) $(CFLAGS) -c -o $@ $<
+vpath %.c ../../lib
 
 $(OFILES): *.h */*.h \
 	../../include/linux/*.h \