Add basic printing/formatting infrastructure for debugging

include/print.h

@@ -0,0 +1,7 @@
+#ifndef PRINT_H
+#define PRINT_H
+
+int print(char *fmt, ...);
+void print_init(void (*putc)(char));
+
+#endif /* PRINT_H */

include/vargs.h

@@ -0,0 +1,14 @@
+#ifndef VARGS_H
+#define VARGS_H
+
+#ifdef __GNUC__
+	typedef __builtin_va_list va_list;
+	#define va_start(v,l) __builtin_va_start(v,l)
+	#define va_end(v) __builtin_va_end(v)
+	#define va_arg(v,l) __builtin_va_arg(v,l)
+	#define va_copy(d,s) __builtin_va_copy(d,s)
+#else
+	#error "Variadic functions aren't supported with any compiler other than GCC."
+#endif
+
+#endif /* VARGS_H */