DnsResolver/res_comp.cpp - fix bugprone-branch-clone warning

Fixes:
  packages/modules/DnsResolver/res_comp.cpp:151:37: error: repeated branch in conditional chain [bugprone-branch-clone,-warnings-as-errors]
          } else if (periodchar(pch)) {
                                      ^
  packages/modules/DnsResolver/res_comp.cpp:153:10: note: end of the original
          } else if (periodchar(nch) || nch == '\0') {
           ^
  packages/modules/DnsResolver/res_comp.cpp:153:52: note: clone 1 starts here
          } else if (periodchar(nch) || nch == '\0') {
                                                     ^

Test: builds
Bug: 153035880
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I30ced2efe9f75c3f0efc0401c38ec83ea9ac9e32