Use the standard stream buffer size for the lexer buffer (#1396)

src/asm/lexer.cpp

@@ -11,7 +11,6 @@
 #include <inttypes.h>
 #include <limits.h>
 #include <math.h>
-#include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unordered_map>