meta: add mailmap entry for dmabupt

This consolidates two email addresses/entries in AUTHORS into one.

PR-URL: #39596
Reviewed-By: Ujjwal Sharma <ryzokuken@disroot.org>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

.mailmap

@@ -445,6 +445,7 @@ Wilson Lin <wla80@sfu.ca>
 Wyatt Preul <wpreul@gmail.com>
 Xavier J Ortiz <xavier.ortiz.ch@gmail.com>
 xiaoyu <306766053@qq.com>
+Xu Meng <dmabupt@gmail.com> <mengxumx@cn.ibm.com>
 Yael Hermon <yaelherm@gmail.com> <yaelhe@wix.com>
 ycjcl868 <45808948@qq.com> <chaolinjin@gmail.com>
 Yingchen Xue <yingchenxue@qq.com>

AUTHORS

@@ -2793,7 +2793,7 @@ Gabriela Niño <gabynr@gmail.com>
 Mike MacCana <mike.maccana@gmail.com>
 Tim Baverstock <tim.baverstock@corp.badoo.com>
 Walle Cyril <cyril.walle@protonmail.com>
-Xu Meng <mengxumx@cn.ibm.com>
+Xu Meng <dmabupt@gmail.com>
 Samuel Attard <sattard@slack-corp.com>
 Ben L. Titzer <titzer@google.com>
 Ojasvi Monga <ojasvi@Ojasvis-MacBook-Air.local>
@@ -3031,7 +3031,6 @@ Sk Sajidul Kadir <sheikh.sajid522@gmail.com>
 Bartlomiej Brzozowski <bart.brzozowski@janeasystems.com>
 Saajan <saajan.sn@gmail.com>
 Yash Ladha <yashladhapankajladha123@gmail.com>
-Xu Meng <dmabupt@gmail.com>
 Alex R <alexei.rudenko@gmail.com>
 Hachimi Aa (Sfeir) <hachimi.aa@sfeir.com>
 Daniel Estiven Rico Posada <danielrico.posada@gmail.com>