[obj2yaml] - Fix the issue with dumping empty sections when dumping program headers.

Imagine we have:

```
ProgramHeaders:
  - Type:  PT_LOAD
    Flags: [ PF_W, PF_R ]
    Sections:
      - Section: .bar
    VAddr: 0x2000
Sections:
  - Name:    .foo
    Type:    SHT_PROGBITS
    Flags:   [ SHF_ALLOC, SHF_EXECINSTR ]
    Address: 0x1000
  - Name:    .bar
    Type:    SHT_PROGBITS
    Flags:   [ SHF_ALLOC, SHF_EXECINSTR ]
    Address: 0x2000
```

Both `.foo` and `.bar` share the same starting file offset,
but `VA(.foo)` < `VA(PT_LOAD)`, we should not include it into segment.

This patch fixes the issue.

Differential revision: https://reviews.llvm.org/D77652