Makefile: add $(STACKREALIGN) to CFLAGS for vp9_reconintra.c

Without this, test_libvpx crashes at
VP9MultiThreadedFrameParallel.PauseSeekResume on OS/2.

Change-Id: I15472738f4166d97cb49868652982d351a291c11

build/make/Makefile

@@ -140,6 +140,8 @@ $(BUILD_PFX)%_avx.c.d: CFLAGS += -mavx $(STACKREALIGN)
 $(BUILD_PFX)%_avx.c.o: CFLAGS += -mavx $(STACKREALIGN)
 $(BUILD_PFX)%_avx2.c.d: CFLAGS += -mavx2 $(STACKREALIGN)
 $(BUILD_PFX)%_avx2.c.o: CFLAGS += -mavx2 $(STACKREALIGN)
+$(BUILD_PFX)%vp9_reconintra.c.d: CFLAGS += $(STACKREALIGN)
+$(BUILD_PFX)%vp9_reconintra.c.o: CFLAGS += $(STACKREALIGN)
 
 $(BUILD_PFX)%.c.d: %.c
 	$(if $(quiet),@echo "    [DEP] $@")