test: redirect existing clang importer tests to test the new mechanism

Author: nkcsgexi

test/ClangImporter/availability_spi_as_unavailable.swift

@@ -1,6 +1,6 @@
 // REQUIRES: OS=macosx
-// RUN: %target-swift-frontend -typecheck %s -F %S/Inputs/frameworks -enable-clang-spi -verify -DNOT_UNDERLYING
-// RUN: %target-swift-frontend -typecheck %s -F %S/Inputs/frameworks -module-name SPIContainer -import-underlying-module -enable-clang-spi -verify
+// RUN: %target-swift-frontend -typecheck %s -F %S/Inputs/frameworks -verify -DNOT_UNDERLYING
+// RUN: %target-swift-frontend -typecheck %s -F %S/Inputs/frameworks -module-name SPIContainer -import-underlying-module -verify
 
 #if NOT_UNDERLYING
 import SPIContainer

test/ClangImporter/availability_spi_as_unavailable_bridging_header.swift

@@ -1,5 +1,5 @@
 // REQUIRES: OS=macosx
-// RUN: %target-swift-frontend -typecheck %s -import-objc-header %S/Inputs/frameworks/SPIContainer.framework/Headers/SPIContainer.h -enable-clang-spi -verify
+// RUN: %target-swift-frontend -typecheck %s -import-objc-header %S/Inputs/frameworks/SPIContainer.framework/Headers/SPIContainer.h -verify
 
 
 @_spi(a) public let a: SPIInterface1

test/ClangImporter/availability_spi_transitive.swift

@@ -1,5 +1,5 @@
 // REQUIRES: OS=macosx
-// RUN: %target-swift-frontend -typecheck %s -F %S/Inputs/frameworks -enable-clang-spi -verify
+// RUN: %target-swift-frontend -typecheck %s -F %S/Inputs/frameworks -verify
 
 import SPIContainerImporter