vim: Import v9.1.1646

* 9.1.1646: MS-Windows: completion cannot handle implicit drive letters
* 9.1.1645: fuzzy.c can be further improved
* 9.1.1644: configure: doesn't separate CPPFLAGS and CFLAGS
* runtime(doc): Update help for the items() function
* 9.1.1643: tabpanel: mouse code too complicated
* 9.1.1642: configure: wrong C99 feature test
* 9.1.1641: a few compiler warnings are output

Author: github-actions[bot]

gitlog.txt

@@ -1 +1 @@
-* [9.1.1640](https://github.com/vim/vim/commit/c08b94b072588d69e0fe76bc93dcd1d8c46be469): Unicode has deprecated some code-points\n* [9.1.1639](https://github.com/vim/vim/commit/1e38198a413f7235c909ccd0d55b339a3e920615): completion: popup may be misplaced\n* [9.1.1638](https://github.com/vim/vim/commit/a09b1604d4fe7516d87fbcbf2ffd2dc484799b23): completion: not possible to delay the autcompletion\n* [runtime(vim): set 'comments' based on script type (legacy/Vim9)](https://github.com/vim/vim/commit/b405c790046fc6758bf4a90feb6a67c2411685a0)\n* [runtime(vim9): Disable shellslash for shellescape() in Open()](https://github.com/vim/vim/commit/39f9298cb2944071b2b19a6b28edf0939aa4312d)\n* [9.1.1637](https://github.com/vim/vim/commit/3281a0ae62be9e48ce4ef1c9cc89503bf5f2bb04): FEAT\_DIFF used in diff.pro\n* [translation(sr): Update Serbian messages translation](https://github.com/vim/vim/commit/90f5d67840d948c6f09557419e9d2a48facfd9a0)\n* [runtime(diff): fix mixed translations in zh\_CN](https://github.com/vim/vim/commit/3cee950fc9f8cdcfe3f168fe83072b2a9eb15d47)\n* [9.1.1636](https://github.com/vim/vim/commit/d6a762fe1b8c51e9d240d71f8724277d7d7f2788): style issues\n* [9.1.1635](https://github.com/vim/vim/commit/62f5be6ea6d0b14eefb5278f4d54002c1ab58aa0): tabpanel: cannot drag inactive tabs
+* [9.1.1646](https://github.com/vim/vim/commit/a2f13bf782f723e116c5d4cc7d79a23e918a24db): MS-Windows: completion cannot handle implicit drive letters\n* [9.1.1645](https://github.com/vim/vim/commit/59799f3afac310f3dca409e295b2ce2036867eaf): fuzzy.c can be further improved\n* [9.1.1644](https://github.com/vim/vim/commit/ce288c7fb05d91fa4bb434485471d65d2045aece): configure: doesn't separate CPPFLAGS and CFLAGS\n* [runtime(doc): Update help for the items() function](https://github.com/vim/vim/commit/308a3130be89148cdaf83bfaf00e3e7c69ed2133)\n* [9.1.1643](https://github.com/vim/vim/commit/20a159b55771d66878dccaa28b84894a4fc4a852): tabpanel: mouse code too complicated\n* [9.1.1642](https://github.com/vim/vim/commit/0ebe55af548e5347fc1e4119e20d5063d17f62d3): configure: wrong C99 feature test\n* [9.1.1641](https://github.com/vim/vim/commit/486cffab3edefdca4daf064fc871c2f4a29bcb6d): a few compiler warnings are output