ladspa-preamp-2-bp153.1.14

- Wrap with a namespace for own exp2() implementation to fix the
  build error with gcc6:
  preamp-ext2-conflict.patch

- Run spec-cleaner
- Remove obsoleted autoreq/autoprov tags

- correct the license to GPL-2.0+

- Split from ladspa package
- Patch carried from the original ladspa package:
  preamp.dif