Build system improvements for windows

- Add EXE extension correctly
- Detect windows with _WIN32 macro and retire UNIX macro

Makefile

@@ -1,5 +1,4 @@
-PROG = tbftss
-CC = gcc
-CXXFLAGS += -DUNIX
+CC=gcc
+EXEEXT=
 
 include common.mk

Makefile.win32

@@ -1,4 +1,4 @@
-PROG = tbftss.exe
+EXEEXT=.exe
 CC=x86_64-w64-mingw32-gcc
 
 include common.mk

common.mk

@@ -1,5 +1,7 @@
 PROG = tbftss
 
+TARGET=$(PROG)$(EXEEXT)
+
 VERSION = 0.4
 REVISION = $(shell date +"%y%m%d")
 DEBUG = 0
@@ -8,7 +10,7 @@ CXXFLAGS += `sdl2-config --cflags` -DVERSION=$(VERSION) -DREVISION=$(REVISION) -
 CXXFLAGS += -Wall -ansi -pedantic -Werror -Wstrict-prototypes
 CXXFLAGS += -g -lefence
 
-LIBS = `sdl2-config --libs` -lSDL2_mixer -lSDL2_image -lSDL2_ttf -lm
+LIBS := `sdl2-config --libs` -lSDL2_mixer -lSDL2_image -lSDL2_ttf -lm
 
 SEARCHPATH += src/ src/battle src/draw src/game src/galaxy src/json src/system src/test
 vpath %.c $(SEARCHPATH)
@@ -38,15 +40,15 @@ OBJS += waypoints.o widgets.o
 DIST_FILES = data gfx manual music sound src LICENSE makefile README.md CHANGELOG
 
 # top-level rule to create the program.
-all: $(PROG)
+all: $(TARGET)
 
 # compiling other source files.
 %.o: %.c %.h $(DEPS)
 	$(CC) $(CFLAGS) $(CXXFLAGS) -c $<
 
 # linking the program.
-$(PROG): $(OBJS)
-	$(CC)  -o $(PROG) $(OBJS) $(LIBS)
+$(TARGET): $(OBJS)
+	$(CC)  -o $@ $(OBJS) $(LIBS)
 
 # prepare an archive for the program
 dist:
@@ -62,6 +64,6 @@ dist:
 
 # cleaning everything that can be automatically recreated with "make".
 clean:
-	$(RM) $(OBJS) $(PROG)
+	$(RM) $(OBJS) $(TARGET)
 
 .PHONY: dist

src/system/init.c

@@ -20,6 +20,10 @@ Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 
 #include "init.h"
 
+#ifndef _WIN32
+#define UNIX 1
+#endif
+
 
 #if UNIX
 static void createSaveFolder(void);
@@ -97,7 +101,7 @@ void initSDL(void)
 	SDL_LogMessage(SDL_LOG_CATEGORY_APPLICATION, SDL_LOG_PRIORITY_INFO, "Game scale factor: %.2f,%.2f\n", app.scaleX, app.scaleY);
 }
 
-#if UNIX
+#ifdef UNIX
 static void createSaveFolder(void)
 {
 	char *userHome;