Update on descriptors

This PR improves the descriptors management.

• Fields computation is simplified and corrected in some corner cases
• Descriptor can now be given a name to improve debug/tracing information
• Tiles can also be individually named if CHAMELEON_KERNELS_TRACE cmake option is enabled
• core_ztile interface is updated to accept descriptor and print log calls (can be disable through environment variable CHAMELEON_COREBLAS_SILENT similarly to STARPU_SILENT)
• Recursive descriptors management is introduced as a first step toward recursive algorithm
• A CHAMELEON_Desc_Print function has been added to help debug the descriptor information (tile size, leading dimensions, ...)

Additionally:

• Fix a small issue with flush in starpu
• Silent warnings issued from the hmat merge
• Add the -Werror option to the CI build to avoid warnings
• Add a chameleon_ceil function to simplify computations in algorithms

control/descriptor.c

@@ -866,6 +866,10 @@ int CHAMELEON_Desc_Destroy(CHAM_desc_t **descptr)
             if ( tile->format == CHAMELEON_TILE_DESC ) {
                 CHAM_desc_t *tiledesc = tile->mat;
 
+                /* Recursive names are allocated internally, we need to free them */
+                if ( tiledesc->name ) {
+                    free( (void*)(tiledesc->name) );
+                }
                 CHAMELEON_Desc_Destroy( &tiledesc );
                 assert( tiledesc == NULL );
             }