[5.8] Add back -no-toolchain-stdlib-rpath when installing sourcekit-lsp on linux

[finagolfin]

Cherrypick of #715

Explanation: Pull #597 incorrectly removed this, as it's still needed on ELF platforms.

This was fine in 5.7.3, but will regress in 5.8 without this pull:

> readelf -d swift-5.*-ubuntu20.04/usr/bin/sourcekit-lsp |ag "File:|runpath"
File: swift-5.7.3-RELEASE-ubuntu20.04/usr/bin/sourcekit-lsp
 0x000000000000001d (RUNPATH)            Library runpath: [$ORIGIN:$ORIGIN/../lib/swift/linux]
File: swift-5.8-DEVELOPMENT-SNAPSHOT-2023-03-07-a-ubuntu20.04/usr/bin/sourcekit-lsp
 0x000000000000001d (RUNPATH)            Library runpath: [/home/build-user/swift-nightly-install/usr/lib/swift/linux:$ORIGIN:$ORIGIN/../lib/swift/linux]

Note the incorrect /home/build-user/... runpath in the 5.8 snapshot, which could be a security issue.

Scope: Only affects the runpath for the sourcekit-lsp executable on linux

SR Issue: None

Risk: None, simply lowers security risk

Testing: The CI was run when this was merged into trunk, including a full toolchain build.

Reviewer: @ahoppen

@airspeedswift, would be good to get this regression corrected before the 5.8 release. I will add an integration test in the coming weeks so that these runpath regressions don't happen again.

[finagolfin]

Ping @airspeedswift, too late to get this into 5.8? Would like to get it into the next patch release if so.

[ahoppen]

@swift-ci Please test

[finagolfin]

Glad to see this in.