don't use SDL in Load_surface() anymore

So the init phase does not depend on SDL anymore.

Signed-off-by: Thomas Bernard <miniupnp@free.fr>

src/Makefile

@@ -577,7 +577,7 @@ OBJS = main.o init.o graph.o $(APIOBJ) misc.o special.o \
        transform.o pversion.o factory.o $(PLATFORMOBJ) \
        fileformats.o miscfileformats.o libraw2crtc.o \
        brush_ops.o buttons_effects.o layers.o \
-       oldies.o tiles.o colorred.o unicode.o
+       oldies.o tiles.o colorred.o unicode.o gfx2surface.o
 ifndef NORECOIL
 OBJS += loadrecoil.o recoil.o
 endif