integrate x86_64-asm.c into i386-asm.c

Also, disable 16bit support for now as it causes bugs
in 32bit mode.  #define I386_ASM_16 if you want it.

i386-gen.c

@@ -109,6 +109,12 @@ void o(unsigned int c)
     }
 }
 
+void gen_le16(int v)
+{
+    g(v);
+    g(v >> 8);
+}
+
 void gen_le32(int c)
 {
     g(c);
@@ -161,6 +167,13 @@ static void gen_addr32(int r, Sym *sym, int c)
     gen_le32(c);
 }
 
+static void gen_addrpc32(int r, Sym *sym, int c)
+{
+    if (r & VT_SYM)
+        greloc(cur_text_section, sym, ind, R_386_PC32);
+    gen_le32(c - 4);
+}
+
 /* generate a modrm reference. 'op_reg' contains the addtionnal 3
    opcode bits */
 static void gen_modrm(int op_reg, int r, Sym *sym, int c)