jump optimizations

jump optimizations

This unifies VT_CMP with VT_JMP(i) by using mostly VT_CMP
with both a positive and a negative jump target list.

Such we can delay putting the non-inverted or inverted jump
until we can see which one is nore suitable (in most cases).

example:
    if (a && b || c && d)
        e = 0;

before this patch:
   a:	8b 45 fc             	mov    0xfffffffc(%ebp),%eax
   d:	83 f8 00             	cmp    $0x0,%eax
  10:	0f 84 11 00 00 00    	je     27 <main+0x27>
  16:	8b 45 f8             	mov    0xfffffff8(%ebp),%eax
  19:	83 f8 00             	cmp    $0x0,%eax
  1c:	0f 84 05 00 00 00    	je     27 <main+0x27>
  22:	e9 22 00 00 00       	jmp    49 <main+0x49>
  27:	8b 45 f4             	mov    0xfffffff4(%ebp),%eax
  2a:	83 f8 00             	cmp    $0x0,%eax
  2d:	0f 84 11 00 00 00    	je     44 <main+0x44>
  33:	8b 45 f0             	mov    0xfffffff0(%ebp),%eax
  36:	83 f8 00             	cmp    $0x0,%eax
  39:	0f 84 05 00 00 00    	je     44 <main+0x44>
  3f:	e9 05 00 00 00       	jmp    49 <main+0x49>
  44:	e9 08 00 00 00       	jmp    51 <main+0x51>
  49:	b8 00 00 00 00       	mov    $0x0,%eax
  4e:	89 45 ec             	mov    %eax,0xffffffec(%ebp)
  51:   ...

with this patch:
   a:	8b 45 fc             	mov    0xfffffffc(%ebp),%eax
   d:	83 f8 00             	cmp    $0x0,%eax
  10:	0f 84 0c 00 00 00    	je     22 <main+0x22>
  16:	8b 45 f8             	mov    0xfffffff8(%ebp),%eax
  19:	83 f8 00             	cmp    $0x0,%eax
  1c:	0f 85 18 00 00 00    	jne    3a <main+0x3a>
  22:	8b 45 f4             	mov    0xfffffff4(%ebp),%eax
  25:	83 f8 00             	cmp    $0x0,%eax
  28:	0f 84 14 00 00 00    	je     42 <main+0x42>
  2e:	8b 45 f0             	mov    0xfffffff0(%ebp),%eax
  31:	83 f8 00             	cmp    $0x0,%eax
  34:	0f 84 08 00 00 00    	je     42 <main+0x42>
  3a:	b8 00 00 00 00       	mov    $0x0,%eax
  3f:	89 45 ec             	mov    %eax,0xffffffec(%ebp)
  42:   ...