pangomm2.48: update to 2.50.2.

2.50.2 (stable):

* Fontset: Use callback functions with C linkage
  (Kjell Ahlstedt) Issue glibmm#1 (Murray Cumming)
* Coverage: Don't use deprecated pango_coverage_ref/unref()
  (Kjell Ahlstedt)

Documentation:
* Doxyfile.in: Don't hide undocumented classes
  (Kjell Ahlstedt)
* README.win32: Convert to MarkDown and rename to README.win32.md
  Make dependencies clearer
  (Chun-wei Fan)
* Remove AUTHORS, HACKING, README.SUN; add general info to README.md
  (Kjell Ahlstedt) Issue gtkmm#140

Meson build:
* Detect if we build from a git subtree
  (William Roy) Merge request gtkmm!72
* Don't copy files with configure_file()
  (Kjell Ahlstedt)
* Fix the evaluation of is_git_build on Windows
  (Kjell Ahlstedt) Issue gtkmm#131 (William Roy)
* Don't fail if warning_level=everything
  (Daniel Boles, Kjell Ahlstedt) Merge request gtkmm!87

2.50.1 (stable):

* Context::get_font_map(): Fix reference count
  (Kjell Ahlstedt)

Build:
* Meson build: Specify 'check' option in run_command()
  Will be necessary with future versions of Meson.
  Require Meson >= 0.55.0
* Meson build: Check if Perl is required for building documentation
* Meson build: Avoid unnecessary configuration warnings
  (Kjell Ahlstedt)
* Meson build: Re-organize warning-related compiler flags for MSVC
  (Chun-wei Fan)

2.50.0 (stable):

* AttrList: Add get_attributes(), update(), equal()
  (Kjell Ahlstedt) Issue #12 (misos1)
* Make CairoFontMap::set_resolution() usable
  by adding the CairoFontMapImpl class
  (Kjell Ahlstedt) Issue #15 (Ievgenii Meshcheriakov)
* Add FontMap::get_family()
  (Kjell Ahlstedt)
* AttrList: Add to_string() and from_string()
  Attribute: Add TextTransform, BaselineShift and FontScle enums
  and some create_attr_*() methods
  (Kjell Ahlstedt)

Build:
* Don't include individual pango headers
  (Matthias Clasen, Kjell Ahlstedt) Merge request !22
* Support Visual Studio 2022 builds
  (Chun-wei Fan)
* Require pango >= 1.49.4
  (Kjell Ahlstedt)

2.49.1 (unstable)

* Layout, LayoutIter: Add get_const_line() and get_const_lines()
  (Kjell Ahlstedt) Issue #10 (misos1)
* GlyphItem: Make most methods public
  (Kjell Ahlstedt) Issue #11 (Josh Bialkowski)


(wiz)