radix tree test suite: Specify -m32 in LDFLAGS too

Michael's patch to use the default make rule for linking and the patch
from Rehas to use -m32 if building a 32-bit test-suite on a 64-bit
platform don't work well together.
Reported-by: Rehas Sachdeva <aquannie@gmail.com>
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>

tools/testing/radix-tree/Makefile

@@ -13,6 +13,7 @@ endif
 
 ifeq ($(BUILD), 32)
 	CFLAGS += -m32
+	LDFLAGS += -m32
 endif
 
 targets: mapshift $(TARGETS)