btrfs-progs: build: link against local libraries

If there's a system provided libbtrfs.0, it will be used for the
library-test build and could miss linker errors, as reported.

Reported-by: Mike Gilbert <floppymaster@gmail.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Makefile.in

@@ -73,7 +73,7 @@ CFLAGS = @CFLAGS@ \
 	 $(EXTRA_CFLAGS)
 
 LDFLAGS = @LDFLAGS@ \
-	  -rdynamic $(EXTRA_LDFLAGS)
+	  -rdynamic -L$(TOPDIR) $(EXTRA_LDFLAGS)
 
 LIBS = @UUID_LIBS@ @BLKID_LIBS@ @ZLIB_LIBS@ @LZO2_LIBS@ -L. -pthread
 LIBBTRFS_LIBS = $(LIBS)