[refactor] reorganize repository

- create one directory per building block in src and include
- keep one directory for tests, \
  otherwise automake make them "test suites"
- move to AC_OPENMP, which is from autoconf 2.62 (2008)
3 jobs for reorganization in 9 minutes and 41 seconds (queued for 1 second)
Status Job ID Name Coverage
  Build
passed #29116
make:generic

00:05:16

passed #29117
make:knl

00:04:21

passed #29115
repoquality

00:00:02