Switch off GSL's default error handler which triggers internally abort()

Description

Switch off GSL's default error handler which triggers internally about() since we don't want to crash but to rather react on the return codes. This is already switched off in some of the places in the code. MR is adding this in other places where GSL routins are called which can trigger abort().

Conformity

• Changelog entry
• Unit tests
• Update INSTALL
• Downport
• Fixes:

When external dependencies are removed

• Reporting to ...