Add more warnings, clean up Makefile output

kernel/Makefile

@@ -1,7 +1,7 @@
 TARGET := kernel
 
 CC              = zig cc -target x86_64-freestanding
-CFLAGS          = -O2
+CFLAGS          = -O2 -Wall -Wextra -Wno-language-extension-token -pedantic -std=gnu11 -pedantic
 LD              = ld -m elf_x86_64
 QEMU            = qemu-system-x86_64
 QEMUFLAGS       = -m 1G -enable-kvm -cpu host
@@ -20,7 +20,7 @@ $(TARGET): $(OBJ)
 	$(LD) $(LDINTERNALFLAGS) $(OBJ) -o $@
 
 obj/%.o: src/%.c $(HFILES)
-	mkdir -p obj
+	@mkdir -p obj
 	$(CC) $(CFLAGS) $(INTERNALCFLAGS) -c $< -o $@
 
 clean: