[interop] fix the libc++ & foundation symbolic interface test on CI by splitting it into two to avoid SDK dependency for one of them

Author: hyp

test/Interop/Cxx/symbolic-imports/indexing-emit-libcxx-no-foundation-symbolic-module-interface.swift

@@ -0,0 +1,16 @@
+// RUN: %empty-directory(%t)
+// RUN: split-file %s %t
+
+// RUN: %target-swift-frontend %t/test.swift -I %t -c -index-system-modules -index-store-path %t/store -enable-experimental-cxx-interop
+// RUN: ls %t/store/interfaces | %FileCheck --check-prefix=FILES %s
+
+// REQUIRES: OS=macosx
+// REQUIRES: cxx-interop-fixed-cf_options
+
+//--- test.swift
+
+import CxxStdlib
+import Foundation
+
+// FILES: std-{{.*}}.pcm.symbolicswiftinterface
+// FILES-NOT: Foundation*

test/Interop/Cxx/symbolic-imports/indexing-emit-libcxx-symbolic-module-interface.swift

@@ -28,7 +28,6 @@ int freeFunction(int x, int y);
 
 import CxxStdlib
 import CxxModule
-import Foundation
 
 // REMARK_NEW: remark: emitting symbolic interface at {{.*}}/interfaces/std-{{.*}}.pcm.symbolicswiftinterface{{$}}
 // REMARK_NEW: remark: emitting symbolic interface at {{.*}}/interfaces/CxxModule-{{.*}}.pcm.symbolicswiftinterface{{$}}
@@ -38,6 +37,5 @@ import Foundation
 
 // FILES: CxxModule-{{.*}}.pcm.symbolicswiftinterface
 // FILES: std-{{.*}}.pcm.symbolicswiftinterface
-// FILES-NOT: Foundation*
 
 // CHECK: // Swift interface for system module 'std'