[lldb][Linux][x86] Watchpoint expression hit reports garbage

Setting watchpoint on a data segment variable reports garbage on being hit:

```
(lldb) target create "wp"
Current executable set to '/root/dhruv/wp' (x86_64).
```

```
(lldb) p &g
(int *) 0x000000000040400c
(lldb) watch set expression -- 0x000000000040400c
Watchpoint created: Watchpoint 1: addr = 0x0040400c size = 8 state = enabled type = m
watchpoint spec = '0x000000000040400c'
watchpoint resources:
#0: addr = 0x00404008 size = 8
#1: addr = 0x00404010 size = 8
Watchpoint 1 hit:

new value: "d"
(lldb) c
Process 3608952 resuming
g address: 0x40400c, value: 100

Watchpoint 1 hit:
old value: "\xc8"
new value: "\xc8"
Process 3608952 stopped
* thread #1, name = 'wp', stop reason = watchpoint 1
frame #0: 0x000000000040116c wp`main at wp.c:6:7
3 int main() {
4 printf("g address: %p, value: %d\n", &g, g);
5 g = 200;
-> 6 g = 300;
7 printf("Final g: %d\n", g);
8 return 0;
9 }
(lldb) p g
(int) 200
(lldb) c
Process 3608952 resuming

Watchpoint 1 hit:
old value: ",\U00000001"
new value: ",\U00000001"
Process 3608952 stopped
* thread #1, name = 'wp', stop reason = watchpoint 1
frame #0: 0x0000000000401177 wp`main at wp.c:7:29
4 printf("g address: %p, value: %d\n", &g, g);
5 g = 200;
6 g = 300;
-> 7 printf("Final g: %d\n", g);
8 return 0;
9 }
```

In contrast, it works fine with `watchpoint set variable g` :
```
(lldb) c
Process 3606443 resuming
g address: 0x40400c, value: 100

Watchpoint 1 hit:
old value: 100
new value: 200
Process 3606443 stopped
* thread #1, name = 'wp', stop reason = watchpoint 1
frame #0: 0x000000000040116c wp`main at wp.c:6:7
3 int main() {
4 printf("g address: %p, value: %d\n", &g, g);
5 g = 200;
-> 6 g = 300;
7 printf("Final g: %d\n", g);
8 return 0;
9 }
```

Reproduce the issue with the supplied wp.c example on Linux x86 using an expression watchpoint, then compare it with `watchpoint set variable g`. Trace the LLDB watchpoint value-reporting path and verify that hits report the actual old and new values, such as 100 and 200, rather than garbage.

Written by the indexing model from the issue text.