* Changed every 'fpic' variant to 'pic'. fixes#2463
Every variant that activates compilation of position independent code
has been changed to 'pic'. Hardcoded compiler flags in packages have
been substituted with `self.compiler.pic_flag`.
* Changed literal uses of '-fpic' to 'self.compiler.pic_flag'
* Add universal build_type variant to CMakePackage
* Override build_type in some packages with different possible values
* Remove reference to no longer existent debug variant
* Update CBTF packages with new build_type variant
* Keep note on build size of LLVM
* Adding Nalu package.
* Fixing flake8 stuff.
* Fixing flake8 stuff.
* Reorganizing trilinos package file a little to make it less verbose.
* Reorganizing trilinos package file for more general use as well as use as a dependency of the Nalu package. Setting fpic as default for yaml-cpp and superlu.
* Explicitly stating fpic variants in dependent packages.
* Updating nalu and trilinos package files with suggested changes.
* Fixing formatting issues. Making suggested changes.
* Fixing formatting.
* Reducing amount of explicit variants in Nalu. Adding suggested changes to Trilinos package file.
* Making suggested changes to Nalu package.
* Turning off superlu-dist variant.
* Cleaning up yaml-cpp file.
* Fixing pnetcdf requirements in trilinos.
