[embedded] Fix an LLVMARCOpts crash by avoiding direct calls to swift_retain/swift_release

[kubamracek]

The attached testcase causes a compiler crash (by using -assert-config Debug -Osize compilation flags). Turns out that the ARC optimizer doesn't like the presense of a direct call to swift_retain and swift_release in any Swift code, which is present in embedded runtime (EmbeddedRuntime.swift). Let's simply avoid that.

These are only created by LLVMARCContract !
UNREACHABLE executed at /Users/kuba/swift-github-main/swift/lib/LLVMPasses/LLVMARCOpts.cpp:99!
Please submit a bug report (https://swift.org/contributing/#reporting-bugs) and include the crash backtrace.
7  swift-frontend           0x0000000104dda3b4 runSwiftARCOpts(llvm::Function&, swift::SwiftRCIdentity&) + 7880
8  swift-frontend           0x0000000104dda480 swift::SwiftARCOptPass::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) + 48
9  swift-frontend           0x00000001092bf0d4 llvm::PassManager<llvm::Function, llvm::AnalysisManager<llvm::Function>>::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) + 308
10 swift-frontend           0x0000000108d5fa20 llvm::CGSCCToFunctionPassAdaptor::run(llvm::LazyCallGraph::SCC&, llvm::AnalysisManager<llvm::LazyCallGraph::SCC, llvm::LazyCallGraph&>&, llvm::LazyCallGraph&, llvm::CGSCCUpdateResult&) + 984
11 swift-frontend           0x0000000108d5bec4 llvm::PassManager<llvm::LazyCallGraph::SCC, llvm::AnalysisManager<llvm::LazyCallGraph::SCC, llvm::LazyCallGraph&>, llvm::LazyCallGraph&, llvm::CGSCCUpdateResult&>::run(llvm::LazyCallGraph::SCC&, llvm::AnalysisManager<llvm::LazyCallGraph::SCC, llvm::LazyCallGraph&>&, llvm::LazyCallGraph&, llvm::CGSCCUpdateResult&) + 376

Fixes rdar://117162118.

[kubamracek]

@swift-ci please test

[eeckstein]

Can we call this an Ouroboros bug? 😄
lgtm!

[kubamracek]

Deal!

git mv test/embedded/arc-crash.swift test/embedded/ouroboros-bug.swift

[kubamracek]

@swift-ci please test