stdlib: Make Result methods inlinable

The "Result" type is expected to have no overhead when used.
This requires the member functions to be inlinable.
Which is probably okay for library evolution, because it's unlikely that those methods change in an incompatible way.

Author: eeckstein

stdlib/public/core/Result.swift

@@ -38,6 +38,7 @@ public enum Result<Success, Failure: Error> {
   ///   instance.
   /// - Returns: A `Result` instance with the result of evaluating `transform`
   ///   as the new success value if this instance represents a success.
+  @inlinable
   public func map<NewSuccess>(
     _ transform: (Success) -> NewSuccess
   ) -> Result<NewSuccess, Failure> {
@@ -75,6 +76,7 @@ public enum Result<Success, Failure: Error> {
   ///   instance.
   /// - Returns: A `Result` instance with the result of evaluating `transform`
   ///   as the new failure value if this instance represents a failure.
+  @inlinable
   public func mapError<NewFailure>(
     _ transform: (Failure) -> NewFailure
   ) -> Result<Success, NewFailure> {
@@ -112,6 +114,7 @@ public enum Result<Success, Failure: Error> {
   ///   instance.
   /// - Returns: A `Result` instance with the result of evaluating `transform`
   ///   as the new failure value if this instance represents a failure.
+  @inlinable
   public func flatMap<NewSuccess>(
     _ transform: (Success) -> Result<NewSuccess, Failure>
   ) -> Result<NewSuccess, Failure> {
@@ -130,6 +133,7 @@ public enum Result<Success, Failure: Error> {
   ///   instance.
   /// - Returns: A `Result` instance, either from the closure or the previous 
   ///   `.success`.
+  @inlinable
   public func flatMapError<NewFailure>(
     _ transform: (Failure) -> Result<Success, NewFailure>
   ) -> Result<Success, NewFailure> {
@@ -157,6 +161,7 @@ public enum Result<Success, Failure: Error> {
   ///
   /// - Returns: The success value, if the instance represents a success.
   /// - Throws: The failure value, if the instance represents a failure.
+  @inlinable
   public func get() throws -> Success {
     switch self {
     case let .success(success):