Use the %target-swift-frontend instead of hardcoding the triple

Author: gribozavr

test/IRGen/abi_v7k.swift

@@ -1,6 +1,7 @@
-// RUN: %swift -target armv7k-apple-watchos2 -emit-ir -primary-file %s -module-name test_v7k | FileCheck %s
-// RUN: %swift -target armv7k-apple-watchos2 -S -primary-file %s -module-name test_v7k | FileCheck -check-prefix=V7K %s
+// RUN: %target-swift-frontend -emit-ir -primary-file %s -module-name test_v7k | FileCheck %s
+// RUN: %target-swift-frontend -S -primary-file %s -module-name test_v7k | FileCheck -check-prefix=V7K %s
 
+// REQUIRES: CPU=armv7k
 // REQUIRES: OS=watchos
 
 // CHECK-LABEL: define hidden float @_TF8test_v7k9addFloats{{.*}}(float, float)