test: fix the broken test

swiftlang/swift-driver#1741 fixed a bug in the swift-driver which
exposed a bug in this test. The use of `%FileCheck` is a problem as that
sanitises the output substituting `BUILD_DIR` for the build directory
that is now properly computed. Because `PATH` is being configured to an
invalid path the actual driver is not found and the test fails.

Author: compnerd

test/Interpreter/shebang-env.swift

@@ -4,8 +4,8 @@
 // RUN: cat %s >> %t.shebang.swift
 // RUN: chmod u+x %t.shebang.swift
 
-// RUN: env PATH=$(dirname %swift_driver_plain) %t.shebang.swift | %FileCheck -check-prefix=NONE %s
-// RUN: env PATH=$(dirname %swift_driver_plain) %t.shebang.swift a b c | %FileCheck -check-prefix=THREE-ARGS %s
+// RUN: env PATH=$(dirname %swift_driver_plain) %t.shebang.swift | %raw-FileCheck -check-prefix=NONE %s
+// RUN: env PATH=$(dirname %swift_driver_plain) %t.shebang.swift a b c | %raw-FileCheck -check-prefix=THREE-ARGS %s
 
 // REQUIRES: swift_interpreter