Log Message:
liblangtag: update to 0.6.3.

0.6.2 -> 0.6.3
=================
Akira TAGOH (3):
      Merged in Edward/liblangtag/Edward/fix-spelling-mistake-1486477267625 \ 
(pull request #9)
      Fix possible null argument for %s directive
      Add ax_check_enable_debug.m4 to satisfy requirement

Caolán McNamara (1):
      enable round tripping ca@valencia locale string back to ca@valencia again

David Tardon (2):
      coverity: fix memory leaks on failure
      coverity: fix more memory leaks

Edward Betts (1):
      fix spelling mistake

caolan (1):
      Merged in caolan/liblangtag (pull request #10)