HPPA dissassembler fix unitialized variables errors

[R33v0LT]

Your checklist for this pull request

• [x] I've documented or updated the documentation of every function and struct this PR changes. If not so I've explained why.
• [x] I've added tests that prove my fix is effective or that my feature works (if possible)

Detailed description

This PR fixes errors like unitialized variables when using clang with flags -Wall -Winvalid-pch -Werror -O3 --std=gnu99 -Werror=sizeof-pointer-memaccess

Test plan

• [x] Make all CI tests successful

Closing issues

closes #2304

[Rot127]

Also, please fill out the complete PR description (I update it for you). We have stricter requirements now. In your case for testing CI green is enough for me.

[kabeor]

Thank you!