Work around arm64 forwarder Linker bug

[wtgodbe]

There appears to be a new Linker bug in producing pure Arm64 Forwarders, as https://learn.microsoft.com/en-us/windows/arm/arm64x-build#building-an-arm64x-pure-forwarder-dll doesn't work out of the box. @lextm provided us with this workaround as a temporary measure.

Revert once https://developercommunity.visualstudio.com/t/LINK-:-error-LNK2001:-unresolved-extern/10932429 is fixed

[Copilot]

Pull Request Overview

This PR implements a workaround for a linker bug that prevents building pure ARM64 forwarders on Windows. The changes modify the build process to ignore linker errors and force building despite unresolved symbols, allowing the build to complete successfully despite the underlying tool issue.

Key changes:

• Add error handling to ignore linker failures during the build process
• Include /FORCE:UNRESOLVED flag to bypass unresolved symbol errors in ARM64X linking
• Ensure build script always exits successfully regardless of intermediate failures

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
build.proj	Adds error handling to continue build execution despite linker failures
build.cmd	Adds /FORCE:UNRESOLVED flag to ARM64X link commands to bypass symbol resolution errors
all.cmd	Forces successful exit code to prevent build failures from propagating

[wtgodbe]

/backport to release/10.0-preview7

[github-actions]

Started backporting to release/10.0-preview7: https://github.com/dotnet/aspnetcore/actions/runs/16622977684

[github-actions]

@wtgodbe backporting to "release/10.0-preview7" failed, the patch most likely resulted in conflicts:

$ git am --3way --empty=keep --ignore-whitespace --keep-non-patch changes.patch

Applying: Work around arm64 forwarder Linker bug
Applying: Add msbuild dependencies to fix SourceBuild prebuilts
Using index info to reconstruct a base tree...
M	eng/Version.Details.xml
M	eng/Versions.props
Falling back to patching base and 3-way merge...
Auto-merging eng/Version.Details.xml
CONFLICT (content): Merge conflict in eng/Version.Details.xml
Auto-merging eng/Versions.props
CONFLICT (content): Merge conflict in eng/Versions.props
error: Failed to merge in the changes.
hint: Use 'git am --show-current-patch=diff' to see the failed patch
hint: When you have resolved this problem, run "git am --continue".
hint: If you prefer to skip this patch, run "git am --skip" instead.
hint: To restore the original branch and stop patching, run "git am --abort".
hint: Disable this message with "git config set advice.mergeConflict false"
Patch failed at 0002 Add msbuild dependencies to fix SourceBuild prebuilts
Error: The process '/usr/bin/git' failed with exit code 128

Please backport manually!