Recommend users use readelf instead of objdump to dump .comment contents.

readelf's output is much easier to read than objdump's as you can see below.

  $ readelf --string-dump .comment foo
  String dump of section '.comment':
    [     1]  GCC: (Ubuntu 4.8.4-2ubuntu1~14.04.3) 4.8.4
    [    2c]  clang version 5.0.0
    [    41]  Linker: LLD 5.0.0

  $ objdump -j .comment -s foo
  Contents of section .comment:
   0000 00474343 3a202855 62756e74 7520342e  .GCC: (Ubuntu 4.
   0010 382e342d 32756275 6e747531 7e31342e  8.4-2ubuntu1~14.
   0020 30342e33 2920342e 382e3400 636c616e  04.3) 4.8.4.clan
   0030 67207665 7273696f 6e20352e 302e3020  g version 5.0.0
   0040 004c696e 6b65723a 204c4c44 20352e30  .Linker: LLD 5.0
   0050 2e3000                               .0.

llvm-svn: 301515