dispatcher: Increase line buffer size

[smititelu]

Pre-Submission Checklist

• Commit message has the format required by CONTRIBUTING guide
• Commits are split per component (core, individual modules, libs, utils, ...)
• Each component has a single commit (if not, squash them into one commit)
• No commits to README files for modules (changes must be done to docbook files
  in doc/ subfolder, the README file is autogenerated)

Type Of Change

• Small bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds new functionality)
• Breaking change (fix or feature that would change existing functionality)

Checklist:

• PR should be backported to stable branches
• Tested changes locally
• Related to issue #XXXX (replace XXXX with an open issue number)

Description

Depending on how many custom attributes one has set in the dispatcher file, some of them might be ignored due to the 256 read line buffer size. Increase the line buffer size. Probably adding a modparam for that would be a better approach ?! but I want to avoid any dynamic alloc/free(for now).