LU factorization with partial pivoting per column (warning: panel only)

This MR adds partial pivoting feature to the LU factorization, however this is done only on the panel for now.

It includes a series of changes to setup the field for this new feature:

• warnings fixes and coverity report bugfix
• renaming of the codelet_zpanel files to the scheme one feature per file, and following the naming : core_zgetrf[_nopiv][percol]{diag,offdiag} or core_zgetrf[_nopiv][percol]{diag,offdiag}
• Add a dedicated CAHM_piv_t descriptor to manage ipiv arrays