Update test_symbolGraphExtract_arguments for new header search strategy

Also lift the macOS restriction now that swiftpm emits the compatibility
header on other platforms.

Author: xymus

Tests/BuildTests/BuildPlanTests.swift

@@ -2127,7 +2127,7 @@ class BuildPlanTestCase: BuildSystemProviderTestCase {
 
         // D
         do {
-            let expectedBModuleMap = AbsolutePath("/path/to/build/\(triple)/debug/B.build/module.modulemap").pathString
+            let expectedBInclude = AbsolutePath("/path/to/build/\(triple)/debug/B.build/include/").pathString
             let expectedCModuleMap = AbsolutePath("/path/to/build/\(triple)/debug/C.build/module.modulemap").pathString
             let expectedDModuleMap = AbsolutePath("/path/to/build/\(triple)/debug/D.build/module.modulemap").pathString
             let expectedModuleCache = AbsolutePath("/path/to/build/\(triple)/debug/ModuleCache").pathString
@@ -2149,13 +2149,11 @@ class BuildPlanTestCase: BuildSystemProviderTestCase {
                 ]
             )
 
-#if os(macOS)
             try XCTAssertMatchesSubSequences(
                 result.moduleBuildDescription(for: "D").symbolGraphExtractArguments(),
                 // Swift Module dependencies
-                ["-Xcc", "-fmodule-map-file=\(expectedBModuleMap)"]
+                ["-Xcc", "-I", "-Xcc", "\(expectedBInclude)"]
             )
-#endif
         }
     }