Update pango to 1.40.0

Overview of changes between 1.39.1 and 1.40.0
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- Fix typos
- Don't treat OGHAM SPACE MARK as whitespace

Overview of changes between 1.38.1 and 1.39.0
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- Update PangoScript to Unicode 8.0

Overview of changes between 1.38.0 and 1.38.1
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- Require 0.9.30
- Fix make check with --enable-debug=no
- Win32 build fixes

Overview of changes between 1.37.5 and 1.38.0
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- No changes

Overview of changes between 1.37.4 and 1.37.5
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- Small optimizations

Overview of changes between 1.37.3 and 1.37.4
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- Use grapheme boundaries in justification
- Support coloring marks and bases independently (#541608)
- Fix a crash (#753167)
- Make Thai and Arabic support thread-safe
- Fix justification (#753772)

Overview of changes between 1.37.2 and 1.37.3
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- Fix pango_glyph_item_iter_prev
- Add alpha attributes
- Add support for alpha in markup

Overview of changes between 1.37.1 and 1.37.2
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- Don't use hb_glib_get_unicode_funcs
- Warning fixes

(prlw1)