nwztools: fix Makefile

Seems like newer versions of mingw will sponteanously add a .exe suffix to
the output path if it doesn't have one, for example mingw-gcc -o scsitool bla
will actually create scsitool.exe and of course this breaks my release script.
Fix this by explicitely adding the .exe to avoid any problem

Change-Id: Ic8019b968b532b2ca612ba0c03977a96c22cee01
diff --git a/utils/nwztools/scsitools/Makefile b/utils/nwztools/scsitools/Makefile
index 53b9014..0267581 100644
--- a/utils/nwztools/scsitools/Makefile
+++ b/utils/nwztools/scsitools/Makefile
@@ -1,17 +1,18 @@
 SCSI_DIR=../../scsi
 DEFINES=
 PREFIX?=
+EXE_EXT?=
 CC=$(PREFIX)gcc
 LD=$(PREFIX)gcc
 NWZ_DB_DIR=../../../firmware/target/hosted/sonynwz
 INCLUDES=-I$(NWZ_DB_DIR) -I$(SCSI_DIR)
 CFLAGS=-std=c99 -Wall $(DEFINES) $(INCLUDES)
 LDFLAGS=-L$(SCSI_DIR) -lrbscsi
-BINS=scsitool
+BINS=scsitool$(EXE_EXT)
 
 all: $(BINS)
 
-scsitool: scsitool.c misc.c para_noise.c $(NWZ_DB_DIR)/nwz-db.c
+scsitool$(EXE_EXT): scsitool.c misc.c para_noise.c $(NWZ_DB_DIR)/nwz-db.c
 	$(MAKE) -C $(SCSI_DIR)
 	$(CC) $(CFLAGS) -o $@ $^ $(LDFLAGS)