Please backport 252cea0 to 15.x

[jakeegan]

The commit 252cea0 is a fix for a build error we're seeing on stage 2 bootstrap on AIX 7.3. The issue for the build error is here: #57229.

commit 252cea037bcad6e1e7236756bcbb4e4ed73e328d
Author: Krzysztof Parzyszek <kparzysz@quicinc.com>
Date:   Thu Aug 18 13:50:20 2022 -0700

    [Hexagon] Add defaulted operator= to classes with defaulted copy ctor
    
    This avoids deprecation warning:
    ```
    warning: definition of implicit copy assignment operator for 'AddrInfo'
    is deprecated because it has a user-declared copy constructor
    [-Wdeprecated-copy]
    ```
    
    This fixes https://github.com/llvm/llvm-project/issues/57229

[jakeegan]

/cherry-pick 252cea0

[llvmbot]

@llvm/issue-subscribers-backend-hexagon

[llvmbot]

/branch llvm/llvm-project-release-prs/issue57921

[llvmbot]

/pull-request llvm/llvm-project-release-prs#166