Remove useless code from updateTag function

[Algiane]

Remove useless code in PMMG_updateTag function

In this function :

• edges (required by the user or not) are first added to the hash table without any tag;
• then we process boundary edges and add the MG_BDY tag;
• Thus, the first time that we call hGet, we found gettag==MG_BDY and the testing that gettag is not MG_REQ always answer;
• in consequence, we add the MG_REQ + MG_NOSURF tag to edges that are not required by the user AND to edges that are required by the user and the part of code related to nosurf command line option is useless.

Test case

The removed lines can be tested on the cube-edgReq.mesh.tgz (the file has first to be uncompressed):

• the edge 7-12 is required by the user
• we can run sequentially ParMmg on this mesh inside a debugger (./bin/parmmg_debug cube-edgReq.mesh -nosurf -v 10 command line);
• the parmesh (1 group, 24 elements) is splitted into 2 groups at the end of the first iteration of adaptation and at the beginning of the load balancing step. Groups are then merged by the PMMG_merge_grps2send function and the PMMG_updateTag function is called to update parallel tags (see bt.txt).
• we can use a breakpoint to inspect the tags stored by the hash table (see attached log.txt)