Flip the Polarity on the Cross-Module Test

Make sure we can effectively turn this feature off instead of on.

Author: CodaFi

test/Driver/cross_module.swift

@@ -1,6 +1,6 @@
 // RUN: %empty-directory(%t/sub)
 // RUN: echo "{\"\": {\"swift-dependencies\": \"cross_module.swiftdeps\"}}" > %t/ofm.json
-// RUN: %swiftc_driver -incremental -emit-module -module-name cross_module -output-file-map=%/t/ofm.json -driver-print-jobs -target x86_64-apple-macosx10.9 %s -enable-experimental-cross-module-incremental-build 2>^1 | %FileCheck -check-prefix ENABLE %s
+// RUN: %swiftc_driver -incremental -emit-module -module-name cross_module -output-file-map=%/t/ofm.json -driver-print-jobs -target x86_64-apple-macosx10.9 %s -disable-incremental-imports 2>^1 | %FileCheck -check-prefix ENABLE %s
 
 // ENABLE: {{bin(/|\\\\)swift(-frontend|c)?(\.exe)?"?}} -frontend -merge-modules
-// ENABLE-SAME: -enable-experimental-cross-module-incremental-build
+// ENABLE-SAME: -disable-incremental-imports