Enable swiftinterface verification with compatiblity headers

Lift the workaround that disabled scheduling the swiftinterface
verification task when a compatibility header is generated. This is an
issue only when the header is also installed, we now expect the build
system to disable the verification when it installs the header.

This issue lead to errors on missing headers and failures to build the
underlying clang module at verification.

rdar://100989723

Author: xymus

Sources/SwiftDriver/Jobs/Planning.swift

@@ -510,13 +510,6 @@ extension Driver {
       // Don't verify by default modules emitted from a merge-module job
       // as it's more likely to be invalid.
       emitModuleSeparately || compilerMode == .singleCompile ||
-      parsedOptions.hasFlag(positive: .verifyEmittedModuleInterface,
-                            negative: .noVerifyEmittedModuleInterface,
-                            default: false),
-
-      // Don't verify by default modules emitting a compatibility header. This is
-      // unsupported as the headers are merged after all archs are built. rdar://90864986
-      self.objcGeneratedHeaderPath == nil ||
       parsedOptions.hasFlag(positive: .verifyEmittedModuleInterface,
                             negative: .noVerifyEmittedModuleInterface,
                             default: false)

Tests/SwiftDriverTests/SwiftDriverTests.swift

@@ -5262,14 +5262,14 @@ final class SwiftDriverTests: XCTestCase {
       XCTAssertFalse(verifyJob.commandLine.contains(.flag("-check-api-availability-only")))
     }
 
-    // Don't verify modules with compatibility headers.
+    // Do verify modules with compatibility headers.
     do {
       var driver = try Driver(args: ["swiftc", "foo.swift", "-emit-module", "-module-name",
                                      "foo", "-emit-module-interface",
                                      "-enable-library-evolution", "-emit-objc-header-path", "foo-Swift.h"],
                               env: envVars)
       let plannedJobs = try driver.planBuild()
-      XCTAssertEqual(plannedJobs.filter( { job in job.kind == .verifyModuleInterface}).count, 0)
+      XCTAssertEqual(plannedJobs.filter( { job in job.kind == .verifyModuleInterface}).count, 1)
     }
   }