Add support for new Android overlay being worked on in swiftlang/swift#72634

Author: finagolfin

Fixtures/DependencyResolution/External/Complex/FisherYates/src/Fisher-Yates_Shuffle.swift

@@ -4,6 +4,8 @@ import Darwin
 import Glibc
 #elseif canImport(Musl)
 import Musl
+#elseif canImport(Android)
+import Android
 #endif
 
 public extension Collection {

Fixtures/Miscellaneous/EchoExecutable/Sources/secho/main.swift

@@ -2,6 +2,8 @@
 	import Glibc
 #elseif canImport(Musl)
 	import Musl
+#elseif canImport(Android)
+	import Android
 #else
 	import Darwin.C
 #endif

Sources/Build/TestObservation.swift

@@ -132,6 +132,8 @@ public func generateTestObservationCode(buildParameters: BuildParameters) -> Str
         @_exported import WinSDK
         #elseif os(WASI)
         @_exported import WASILibc
+        #elseif canImport(Android)
+        @_exported import Android
         #else
         @_exported import Darwin.C
         #endif

Sources/CoreCommands/SwiftCommandState.swift

@@ -39,6 +39,8 @@ import Darwin
 import Glibc
 #elseif canImport(Musl)
 import Musl
+#elseif canImport(Android)
+import Android
 #endif
 
 import func TSCBasic.exec