Fix TBI test.

Now we perform the correct check: making sure that we have TBI on for
iOS7.0-Earlier and on for iOS8.0+Later.

The actual functionality that occurs is that we /always/ have TBI on when the
triple is an AArch64 target. Then the backend determines via the triple whether
it is supported or not for the specific os version.

I also removed the executable test bit requires since this test does not execute
anything, it just runs FileCheck tests.

Author: gottesmm

test/Misc/tbi.swift

@@ -1,15 +1,15 @@
 // RUN: %target-build-swift -target arm64-apple-ios8.0 -target-cpu cyclone \
-// RUN:                          -O -S %s -parse-as-library | \
+// RUN:   -O -S %s -parse-as-library | \
 // RUN:   FileCheck --check-prefix=TBI %s
 
-// RUN: %target-build-swift -target arm64-apple-ios8.0 -target-cpu cyclone \
+// RUN: %target-build-swift -target arm64-apple-ios7.0 -target-cpu cyclone \
 // RUN:     -O -S %s -parse-as-library | \
 // RUN:   FileCheck --check-prefix=NO_TBI %s
-// REQUIRES: executable_test
 
 // REQUIRES: CPU=arm64, OS=ios
 
-// Verify that TBI is on by default in Swift.
+// Verify that TBI is on by default in Swift on targets that support it. For our
+// purposes this means iOS8.0 or later.
 
 func f(i: Int) -> Int8 {
   let j = i & 0xff_ffff_ffff_ffff