dev-python/uharfbuzz: add 0.21.0, drop 0.16.1

Signed-off-by: Alessandro Barbieri <lssndrbarbieri@gmail.com>

dev-python/uharfbuzz/files/uharfbuzz-0.16.1-system-harfbuzz.patch

@@ -1,23 +0,0 @@
---- a/setup.py
-+++ b/setup.py
-@@ -13,7 +13,7 @@
- with open(os.path.join(here, 'README.md'), encoding='utf-8') as f:
-     long_description = f.read()
- 
--define_macros = [('HB_NO_MT', '1'), ('HB_EXPERIMENTAL_API', '1')]
-+define_macros = [('HB_EXPERIMENTAL_API', '1')]
- linetrace = False
- if int(os.environ.get('CYTHON_LINETRACE', '0')):
-     linetrace = True
-@@ -30,8 +30,9 @@
- extension = Extension(
-     'uharfbuzz._harfbuzz',
-     define_macros=define_macros,
--    include_dirs=['harfbuzz/src'],
--    sources=['src/uharfbuzz/_harfbuzz.pyx', 'harfbuzz/src/harfbuzz.cc'],
-+    include_dirs=['/usr/include/harfbuzz'],
-+    libraries=['harfbuzz'],
-+    sources=['src/uharfbuzz/_harfbuzz.pyx'],
-     language='c++',
-     extra_compile_args=extra_compile_args,
-     extra_link_args=extra_link_args,