Swap to use %target-swiftc_driver for test

Author: DavidGoldman

test/DebugInfo/debug_prefix_map.swift

@@ -1,6 +1,6 @@
 // RUN: %empty-directory(%t)
 // RUN: %target-swift-frontend -emit-module-path %t/Globals.swiftmodule %S/Globals.swift
-// RUN: %swiftc_driver -g -debug-prefix-map %/S=/var/empty -debug-prefix-map %t=/var/empty %/s -I %t -emit-ir -o - | %FileCheck %s
+// RUN: %target-swiftc_driver -g -debug-prefix-map %/S=/var/empty -debug-prefix-map %t=/var/empty %/s -I %t -emit-ir -o - | %FileCheck %s
 
 import Globals