Makefile: add USE_E9 to the preprocessor flags and make the relevant files understand it

src/arch/x86_64/e9.c

@@ -1,12 +1,16 @@
 #include <arch/io.h>
 
 void e9_putc(char c){
+	#ifdef USE_E9 
 	outb(0xE9, c);
+	#endif
 }
 
 void e9_puts(char* s){
+	#ifdef USE_E9 
 	size_t len = strlen(s);
 
 	for(uintmax_t i = 0; i < len; ++i)
 		outb(0xE9, s[i]);
+	#endif
 }

src/arch/x86_64/e9out.c

@@ -2,6 +2,8 @@
 #include <arch/e9.h>
 #include <sys/stat.h>
 
+#ifdef USE_E9
+
 #include <stddef.h>
 #include <stdint.h>
 
@@ -26,3 +28,5 @@ static devcalls calls = {
 void e9out_init(){
 	devman_newdevice("e9out", TYPE_CHARDEV, MAJOR_E9OUT, 0, &calls);
 }
+
+#endif

src/arch/x86_64/main.c

@@ -66,8 +66,12 @@ void kmain(){
 	consoledev_init();
 
 	pseudodevs_init();
+	
+	#ifdef USE_E9
 
 	e9out_init();
+
+	#endif
 	
 	fb_init();