stdlib: More SE-0193 updates

Author: slavapestov

stdlib/public/SDK/Foundation/NSStringAPI.swift

@@ -436,7 +436,6 @@ extension StringProtocol where Index == String.Index {
   // self can be a Substring so we need to subtract/add this offset when
   // passing _ns to the Foundation APIs. Will be 0 if self is String.
   @inlinable
-  @usableFromInline
   internal var _substringOffset: Int {
     return self.startIndex.encodedOffset
   }
@@ -448,7 +447,6 @@ extension StringProtocol where Index == String.Index {
   }
 
   @inlinable
-  @usableFromInline
   internal func _toRelativeNSRange(_ r: Range<String.Index>) -> NSRange {
     return NSRange(
       location: r.lowerBound.encodedOffset - _substringOffset,

stdlib/public/core/LifetimeManager.swift

@@ -162,7 +162,7 @@ public func withUnsafePointer<T, Result>(
 ///     type. If you need to mutate the argument through the pointer, use
 ///     `withUnsafeMutablePointer(to:_:)` instead.
 /// - Returns: The return value, if any, of the `body` closure.
-@_inlineable
+@inlinable
 public func withUnsafePointer<T, Result>(
   to value: inout T,
   _ body: (UnsafePointer<T>) throws -> Result

stdlib/public/core/UnsafeRawBufferPointer.swift.gyb

@@ -805,7 +805,7 @@ public func withUnsafeBytes<T, Result>(
 ///     If you want to mutate a value by writing through a pointer, use
 ///     `withUnsafeMutableBytes(of:_:)` instead.
 /// - Returns: The return value, if any, of the `body` closure.
-@_inlineable
+@inlinable
 public func withUnsafeBytes<T, Result>(
   of value: T,
   _ body: (UnsafeRawBufferPointer) throws -> Result