Update framework-header-fix to force system sed

Summary:
There are 2 changes here:

1. Use system sed instead of the sed found in the user's path. This
     fixes this script in the case the user has gnu-sed in their $PATH before
     bsd sed since `-i ''` isn't compatible and you need `-i` instead.

2. `set -e` in this script so it fails as soon as one of these commands
     fail instead of throwing errors for each file if they fail

Since this is only ran on macOS, and we're already using this
absolute path below, this seems like a safe addition

Reviewers: kastiglione, beanz

Reviewed By: kastiglione

Subscribers: lldb-commits

Differential Revision: https://reviews.llvm.org/D49776

llvm-svn: 346099