Use fLTO to reduce the binary size

Makefile

@@ -19,7 +19,7 @@ dir_build := build
 dir_out := out
 
 ASFLAGS := -mlittle-endian -mcpu=arm946e-s -march=armv5te
-CFLAGS := -Wall -Wextra -MMD -MP -marm $(ASFLAGS) -fno-builtin -fshort-wchar -std=c11 -Wno-main -O2 -ffast-math
+CFLAGS := -Wall -Wextra -MMD -MP -marm $(ASFLAGS) -fno-builtin -fshort-wchar -std=c11 -Wno-main -O2 -flto -ffast-math
 FLAGS := name=$(name).dat dir_out=$(abspath $(dir_out)) ICON=$(abspath icon.png) APP_DESCRIPTION="Noob-friendly 3DS CFW." APP_AUTHOR="Reisyukaku/Aurora Wright" --no-print-directory
 
 objects_cfw = $(patsubst $(dir_source)/%.s, $(dir_build)/%.o, \
@@ -114,7 +114,7 @@ $(dir_build)/%.o: $(dir_source)/%.s
 
 $(dir_build)/fatfs/%.o: $(dir_source)/fatfs/%.c
 	@mkdir -p "$(@D)"
-	$(COMPILE.c) -Wno-unused-function $(OUTPUT_OPTION) $<
+	$(COMPILE.c) $(OUTPUT_OPTION) $<
 
 $(dir_build)/fatfs/%.o: $(dir_source)/fatfs/%.s
 	@mkdir -p "$(@D)"

loader/Makefile

@@ -29,7 +29,7 @@ SOURCES		:=	source source/fatfs source/fatfs/sdmmc source/fatfs/option
 #---------------------------------------------------------------------------------
 ARCH	:=	-mthumb -mthumb-interwork
 
-CFLAGS	:=	-g -Wall -O2\
+CFLAGS	:=	-g -Wall -O2 -flto\
 			-march=armv5te -mtune=arm946e-s\
 			-ffast-math -Wno-main -std=c99\
 			$(ARCH)

screeninit/Makefile

@@ -29,7 +29,7 @@ SOURCES		:=	source
 #---------------------------------------------------------------------------------
 ARCH	:=	-mthumb -mthumb-interwork
 
-CFLAGS	:=	-g -Wall -O2\
+CFLAGS	:=	-g -Wall -O2 -flto\
 			-mcpu=mpcore -mlittle-endian\
 			-ffast-math -Wno-main -std=c99\
 			$(ARCH)

source/memory.c

@@ -17,7 +17,7 @@ void memcpy(void *dest, const void *src, u32 size)
         destc[i] = srcc[i];
 }
 
-void memset(void *dest, int filler, u32 size)
+void  __attribute__((used)) memset(void *dest, int filler, u32 size)
 {
     u8 *destc = (u8 *)dest;