Disable BTI for now.

Bug: https://issuetracker.google.com/216395195
Test: readelf -aW libc.so | grep PROPERTY
Change-Id: I4d157cbe5bf5b54cb7d3c4efe8fb74d4f72af6f3
diff --git a/cc/config/arm64_device.go b/cc/config/arm64_device.go
index 2d6bcb8..979c825 100644
--- a/cc/config/arm64_device.go
+++ b/cc/config/arm64_device.go
@@ -33,7 +33,9 @@
 		},
 		"armv8-a-branchprot": []string{
 			"-march=armv8-a",
-			"-mbranch-protection=standard",
+			// Disable BTI until drm vendors stop using OS libraries as sources
+			// of gadgets (https://issuetracker.google.com/216395195).
+			"-mbranch-protection=pac-ret",
 		},
 		"armv8-2a": []string{
 			"-march=armv8.2-a",