[SOL] Implement atomic swap #182

Job	Run time
abi-dump-setup	1m 52s
Test lld / Lit Tests (ubuntu-latest)	9m 12s
Build lldb / Lit Tests (ubuntu-latest)	20m 2s
Test lld / Lit Tests (windows-2019)	2m 56s
Test llvm,clang,libclc / Lit Tests (ubuntu-latest)	45m 7s
Build lldb / Lit Tests (windows-2019)	1m 56s
Test lld / Lit Tests (macOS-latest)	9m 45s
Build lldb / Lit Tests (macOS-latest)	15m 55s
Test llvm,clang,libclc / Lit Tests (windows-2019)	1m 58s
Test llvm,clang,libclc / Lit Tests (macOS-latest)	1h 0m 6s
abi-dump (build-baseline)	32m 59s
abi-dump (build-latest)	32m 50s
abi-compare	33s
	3h 55m 11s

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