Hide CFI behind a global flag.

This CL ensures that locally enabling CFI in a .bp file is not honored
unless it is enabled globally using ENABLE_CFI=true first, effectively
hiding it behind a flag.

Bug: 30227045
Bug: 22033465
Test: m -j40 works and device boots
Test: cfi is correctly honored only when the global flag is set.
Change-Id: Iccc6e4bf5e7828ab8ce6056f3e40922712faa0d8
diff --git a/android/config.go b/android/config.go
index 6d28680..3603477 100644
--- a/android/config.go
+++ b/android/config.go
@@ -398,6 +398,10 @@
 	return append([]string(nil), c.ProductVariables.SanitizeDeviceArch...)
 }
 
+func (c *config) EnableCFI() bool {
+	return Bool(c.ProductVariables.EnableCFI)
+}
+
 func (c *config) Android64() bool {
 	for _, t := range c.Targets[Device] {
 		if t.Arch.ArchType.Multilib == "lib64" {