x11-toolkits/pango: Update to 1.56.1
Avoid manual intervention for PLIST_SUB variables for the forseeable
future to ease maintenance. Upstream has been following a predictable
pattern in shared object naming for many years. Drop the VERSION sub; it
hasn't been used for 10+ years now.
Rename the custom THAI option to the standard LANG_TH option.
Whitespace-align blocks and fix tests.