[BoundsSafety] Partially Upstream support for BS_CHK_LibCAttributes for Apple platforms

[delcypher]

This adds the compiler side implementation of the new BS_CHK_LibCAttributes bounds check for the Darwin toolchain. When -fbounds-safety-bringup-missing-checks=libc_attributes is enabled and when compiling for Apple platforms with a userspace Libc the __LIBC_STAGED_BOUNDS_SAFETY_ATTRIBUTES macro is enabled. This macro communicates to Libc that it should switch on the new -fbounds-safety annotations.

rdar://149243724
(cherry picked from commit 6829d4a)

[delcypher]

@swift-ci test llvm

[delcypher]

@swift-ci test

[delcypher]

This is a prerequisite for implementing rdar://148623233.

[delcypher]

macOS LLVM testing failed with:

Resolving deltas:  54% (3768670/6938742)
error: inflate: data stream error (incorrect data check)
fatal: packed object 626036e3cda8aa8621a94399c990c4c376836561 (stored in .git/objects/pack/pack-aed502d313b6b9fb1a7e84d479d19f285da4681d.pack) is corrupt
fatal: fetch-pack: invalid index-pack output

	at org.jenkinsci.plugins.gitclient.CliGitAPIImpl.launchCommandIn(CliGitAPIImpl.java:2846)
	at org.jenkinsci.plugins.gitclient.CliGitAPIImpl.launchCommandWithCredentials(CliGitAPIImpl.java:2185)
	at org.jenkinsci.plugins.gitclient.CliGitAPIImpl$1.execute(CliGitAPIImpl.java:635)
	at org.jenkinsci.plugins.gitclient.RemoteGitImpl$CommandInvocationHandler$GitCommandMasterToSlaveCallable.call(RemoteGitImpl.java:170)
	at org.jenkinsci.plugins.gitclient.RemoteGitImpl$CommandInvocationHandler$GitCommandMasterToSlaveCallable.call(RemoteGitImpl.java:161)
	at hudson.remoting.UserRequest.perform(UserRequest.java:211)
	at hudson.remoting.UserRequest.perform(UserRequest.java:54)
	at hudson.remoting.Request$2.run(Request.java:377)
	at hudson.remoting.InterceptingExecutorService.lambda$wrap$0(InterceptingExecutorService.java:78)
	at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
	at java.base/java.lang.Thread.run(Thread.java:829)
	Suppressed: hudson.remoting.Channel$CallSiteStackTrace: Remote call to macos-node-i-0acee461ffa311514
		at hudson.remoting.Channel.attachCallSiteStackTrace(Channel.java:1787)
		at hudson.remoting.UserRequest$ExceptionResponse.retrieve(UserRequest.java:356)
		at hudson.remoting.Channel.call(Channel.java:1003)
		at org.jenkinsci.plugins.gitclient.RemoteGitImpl$CommandInvocationHandler.execute(RemoteGitImpl.java:153)
		at jdk.internal.reflect.GeneratedMethodAccessor430.invoke(Unknown Source)
		at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
		at java.base/java.lang.reflect.Method.invoke(Method.java:566)
		at org.jenkinsci.plugins.gitclient.RemoteGitImpl$CommandInvocationHandler.invoke(RemoteGitImpl.java:138)
		at com.sun.proxy.$Proxy87.execute(Unknown Source)
		at hudson.plugins.git.GitSCM.fetchFrom(GitSCM.java:997)
		at hudson.plugins.git.GitSCM.retrieveChanges(GitSCM.java:1241)
		at hudson.plugins.git.GitSCM.checkout(GitSCM.java:1305)
		at org.jenkinsci.plugins.workflow.steps.scm.SCMStep.checkout(SCMStep.java:136)
		at org.jenkinsci.plugins.workflow.steps.scm.SCMStep$StepExecutionImpl.run(SCMStep.java:101)
		at org.jenkinsci.plugins.workflow.steps.scm.SCMStep$StepExecutionImpl.run(SCMStep.java:88)
		at org.jenkinsci.plugins.workflow.steps.SynchronousNonBlockingStepExecution.lambda$start$0(SynchronousNonBlockingStepExecution.java:47)
		at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
		at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
		at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
		at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
		at java.base/java.lang.Thread.run(Thread.java:829)
ERROR: Error fetching remote repo 'origin'
ERROR: Maximum checkout retry attempts reached, aborting

[delcypher]

@swift-ci test llvm