Treat warnings as errors by adding -Werror

Add the -Werror flag to the CFLAGS to treat all warnings as errors
during the build process. This ensures that warnings are blocked by CI,
enforcing cleaner code and preventing builds from succeeding with any
warnings

Author: eleanorLYJ

Makefile

@@ -7,7 +7,7 @@ BIN := $(OUT)/rv32emu
 CONFIG_FILE := $(OUT)/.config
 -include $(CONFIG_FILE)
 
-CFLAGS = -std=gnu99 -O2 -Wall -Wextra
+CFLAGS = -std=gnu99 -O2 -Wall -Wextra -Werror
 CFLAGS += -Wno-unused-label
 CFLAGS += -include src/common.h -Isrc/