don't use AC_CANONICAL_TARGET in libtiff configure: this is unnecessary as it's not...

don't use AC_CANONICAL_TARGET in libtiff configure: this is unnecessary as it's not a cross-compiler and also doesn't work when running it as sub-configure when caching is enabled (because the host and the build aliases are cached by the top level configure but the target one is not and autoconf-generated code doesn't deal with this situation correctly)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@58914 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775