nunit-2.6.4-bp152.3.24

- change pkgconfig-file generation logic - protect it from being broken by OBS source_validators
- nunit.pc pkgconfig-file: typo at Libs section ("r" instead of "-r" for some deps)
- added csc-delay-sign.patch: use delay-sign flag when using roslyn "csc" compiler
  * patch applied only when csc compiler detected
- added support for compiling project with roslyn "csc" compiler (that will replace mcs in mono 5.0):
  * manually sign affected assemlies before adding it to GAC

- avoid the broken release ZIP file https://github.com/nunit/nunitv2/issues/35
- fix the pkgconfig file for MonoDevelop
- build with Debug symbols
- place copies into the global assembly cache

- initial packaging