Remove unused _exit function

Firmware/RISCV/stubs/_exit.c

@@ -4,7 +4,7 @@
 
 #include "stub.h"
 
-
+#if 0
 void _exit(int code)
 {
   const char message[] = "\nProgram has exited with code:";
@@ -15,3 +15,4 @@ void _exit(int code)
 
   for (;;);
 }
+#endif

Template/Makefile

@@ -13,7 +13,7 @@ TARGET = gd32vf103
 # debug build?
 DEBUG = 1
 # optimization
-OPT = -O2
+OPT = -O2 #-flto
 
 # Build path
 BUILD_DIR = build
@@ -103,7 +103,7 @@ LDSCRIPT = $(FIRMWARE_DIR)/RISCV/env_Eclipse/GD32VF103x8.lds
 # libraries
 #LIBS = -lc_nano -lm
 LIBDIR = 
-LDFLAGS = -flto $(ARCH) -T$(LDSCRIPT) $(LIBDIR) $(LIBS) $(PERIFLIB_SOURCES) -Wl,--cref -Wl,--no-relax -Wl,--gc-sections -Wl,-M=$(BUILD_DIR)/$(TARGET).map -nostartfiles #-ffreestanding -nostdlib
+LDFLAGS = $(OPT) $(ARCH) -T$(LDSCRIPT) $(LIBDIR) $(LIBS) $(PERIFLIB_SOURCES) -Wl,--cref -Wl,--no-relax -Wl,--gc-sections -Wl,-M=$(BUILD_DIR)/$(TARGET).map -nostartfiles #-ffreestanding -nostdlib
 
 # default action: build all
 all: $(BUILD_DIR)/$(TARGET).elf $(BUILD_DIR)/$(TARGET).hex $(BUILD_DIR)/$(TARGET).bin