llvm-objdump: Some style cleanups to follow LLVM coding style

Rename "ec" to "EC", and rename some iterators.

Then fix whitespace using clang-format-diff.

(As requested in http://llvm-reviews.chandlerc.com/D2559)

Differential Revision: http://llvm-reviews.chandlerc.com/D2594

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@200053 91177308-0d34-0410-b5e6-96231b3b80d8