Add -runtime-compatibility-version none to the VFE/WME LTO tests to workaround a linker failure

[kubamracek]

This is a speculative change to address the ongoing test failures on https://ci.swift.org/view/Dashboard/job/oss-swift_tools-RA_stdlib-DA_test-simulators/2311/console. I don't actually understand why they're failing, and it also doesn't look like we can pinpoint a particular commit where this started happening. But we can't leave the tests failing, so trying this for now.

Failed Tests (2):
  Swift(macosx-x86_64) :: IRGen/virtual-function-elimination-two-modules.swift
  Swift(macosx-x86_64) :: IRGen/witness-method-elimination-two-modules.swift

ld: reference to symbol (which has not been assigned an address) __ZN5swift7FlagSetIjE10lowMaskForILj1EEEjv in '__ZN5swift7FlagSetIjE7maskForILj26ELj1EEEjv' from /Users/ec2-user/jenkins/workspace/oss-swift_tools-RA_stdlib-DA_test-simulators/build/Ninja-ReleaseAssert/swift-macosx-x86_64/lib/swift/macosx/libswiftCompatibility56.a(Task.cpp.o)
<unknown>:0: error: link command failed with exit code 1 (use -v to see invocation)

rdar://107987502

[kubamracek]

@swift-ci please test