Enable safe ICF for all devices

--icf=safe has been enabled for arm and arm64.
Do the same thing for all devices.

On bertha_x86_64, this CL makes system.raw.img 4.4MB smaller.

Bug: 182446785
Test: build

Change-Id: Ifd597cd8496c49b55df269f22e01b1c50dc8f6e8
diff --git a/cc/config/global.go b/cc/config/global.go
index 7e80900..ed18300 100644
--- a/cc/config/global.go
+++ b/cc/config/global.go
@@ -97,6 +97,7 @@
 		"-Wl,--exclude-libs,libgcc_stripped.a",
 		"-Wl,--exclude-libs,libunwind_llvm.a",
 		"-Wl,--exclude-libs,libunwind.a",
+		"-Wl,--icf=safe",
 	}
 
 	deviceGlobalLldflags = append(ClangFilterUnknownLldflags(deviceGlobalLdflags),