Remove check for maximum symbol name length.

Remove check for maximum symbol name length.

        PR fortran/87103
        * expr.c (gfc_check_conformance): Check vsnprintf for truncation.
        * iresolve.c (gfc_get_string): Likewise.
        * symbol.c (gfc_new_symbol): Remove check for maximum symbol
        name length.  Remove redundant 0 setting of new calloc()ed
        gfc_symbol.