[llvm-objdump] Print a blank row at the end of sections

Summary:
When using option `-x` (--all-headers), it will print `Sections`, `Symbol Table`, `Program Header` ...
`Sections` and `Symbol Table` will be connected together.

Before:
```
Sections:
Idx Name          Size      Address          Type
  0               00000000 0000000000000000
  ...
  29 .shstrtab     0000011a 0000000000000000
SYMBOL TABLE:
  ...
```

After:
```
Sections:
Idx Name          Size      Address          Type
  0               00000000 0000000000000000
  ...
  29 .shstrtab     0000011a 0000000000000000

SYMBOL TABLE:
  ...
```

Reviewers: Higuoxing

Reviewed By: Higuoxing

Subscribers: llvm-commits, jhenderson

Differential Revision: https://reviews.llvm.org/D54665

llvm-svn: 347135

tools/llvm-objdump/llvm-objdump.cpp

@@ -1914,6 +1914,7 @@ void llvm::PrintSectionHeaders(const ObjectFile *Obj) {
                      (unsigned)Section.getIndex(), Name.str().c_str(), Size,
                      Address, Type.c_str());
   }
+  outs() << "\n";
 }
 
 void llvm::PrintSectionContents(const ObjectFile *Obj) {