ExecutionDepsFix refactoring:

- Remove unneeded includes and unneeded members
- Use range iterators
- Variable renaming, typedefs, extracting constants
- Removing {} from one line ifs

This patch is NFC.

This is the one of multiple patches that fix bugzilla https://bugs.llvm.org/show_bug.cgi?id=33869
Most of the patches are intended at refactoring the existent code.

Additional relevant reviews:
https://reviews.llvm.org/D40330
https://reviews.llvm.org/D40332
https://reviews.llvm.org/D40333
https://reviews.llvm.org/D40334

Differential Revision: https://reviews.llvm.org/D40331

Change-Id: Ib59060ab3fa5bee3bf2ca2045c24e572635ee7f6
llvm-svn: 323088