unix/linux: update glibc to 2.39

Change-Id: I5c2b996180073ca10f1b7c86201a19eaf0557e43
GitHub-Last-Rev: a092f56935c2d7fb64fc9d3922806b2e9e40e143
GitHub-Pull-Request: golang/sys#195
Reviewed-on: https://go-review.googlesource.com/c/sys/+/585136
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

unix/linux/mkall.go

@@ -417,6 +417,20 @@ func (t *target) makeHeaders() error {
 	} else {
 		glibcArgs = append(glibcArgs, "--enable-kernel="+MinKernel)
 	}
+
+	// CET is not supported on x86 but glibc 2.39 enables it by default, it was later reverted.
+	// See https://sourceware.org/git/?p=glibc.git;a=commit;h=25f1e16ef03a6a8fb1701c4647d46c564480d88c
+	if t.LinuxArch == "x86" {
+		glibcArgs = append(glibcArgs, "--enable-cet=no")
+	}
+
+	// glibc 2.38 requires libmvec to be disabled explicitly in aarch64
+	// since the installed compiler does not have SVE ACLE.
+	// See https://sourceware.org/pipermail/libc-alpha/2023-May/147829.html
+	if t.LinuxArch == "arm64" {
+		glibcArgs = append(glibcArgs, "--disable-mathvec")
+	}
+
 	glibcConf := t.makeCommand(confScript, glibcArgs...)
 
 	glibcConf.Dir = buildDir