Revert to `-fstack-protector-strong` in read barrier config.

Instead of `-fstack-protector`, which was used temporarily
for performance reasons.

Test: m test-art-host
Bug: 26744236
Bug: 12687968
Change-Id: Ifefa93ef40249b616b278692907c1f9d9b6d41b6
diff --git a/build/art.go b/build/art.go
index 84269c3..999ece6 100644
--- a/build/art.go
+++ b/build/art.go
@@ -68,10 +68,6 @@
 		asflags = append(asflags,
 			"-DART_USE_READ_BARRIER=1",
 			"-DART_READ_BARRIER_TYPE_IS_"+barrierType+"=1")
-
-		// Temporarily override -fstack-protector-strong with -fstack-protector to avoid a major
-		// slowdown with the read barrier config. b/26744236.
-		cflags = append(cflags, "-fstack-protector")
 	}
 
 	if envTrue(ctx, "ART_USE_VIXL_ARM_BACKEND") {