[abi] make the compatibility symbols internal

Author: glessard

stdlib/public/core/UnsafeBufferPointer.swift.gyb

@@ -744,8 +744,10 @@ extension Unsafe${Mutable}BufferPointer {
 % else:
   @_silgen_name("$sSR17withMemoryRebound2to_qd_0_qd__m_qd_0_SRyqd__GKXEtKr0_lF")
 % end
-  public func _legacy_se0333_withMemoryRebound<T, Result>(
-    to type: T.Type, _ body: (${Self}<T>) throws -> Result
+  @usableFromInline
+  internal func _legacy_se0333_withMemoryRebound<T, Result>(
+    to type: T.Type,
+    _ body: (${Self}<T>) throws -> Result
   ) rethrows -> Result {
     if let base = _position {
       _debugPrecondition(MemoryLayout<Element>.stride == MemoryLayout<T>.stride)

stdlib/public/core/UnsafePointer.swift

@@ -327,7 +327,10 @@ public struct UnsafePointer<Pointee>: _Pointer {
   // binary compiled against the stlib binary for Swift 5.6 and older.
   @available(*, unavailable)
   @_silgen_name("$sSP17withMemoryRebound2to8capacity_qd_0_qd__m_Siqd_0_SPyqd__GKXEtKr0_lF")
-  public func _legacy_se0333_withMemoryRebound<T, Result>(to type: T.Type, capacity count: Int,
+  @usableFromInline
+  internal func _legacy_se0333_withMemoryRebound<T, Result>(
+    to type: T.Type,
+    capacity count: Int,
     _ body: (UnsafePointer<T>) throws -> Result
   ) rethrows -> Result {
     Builtin.bindMemory(_rawValue, count._builtinWordValue, T.self)
@@ -1013,7 +1016,10 @@ public struct UnsafeMutablePointer<Pointee>: _Pointer {
   // binary compiled against the stlib binary for Swift 5.6 and older.
   @available(*, unavailable)
   @_silgen_name("$sSp17withMemoryRebound2to8capacity_qd_0_qd__m_Siqd_0_Spyqd__GKXEtKr0_lF")
-  public func _legacy_se0333_withMemoryRebound<T, Result>(to type: T.Type, capacity count: Int,
+  @usableFromInline
+  internal func _legacy_se0333_withMemoryRebound<T, Result>(
+    to type: T.Type,
+    capacity count: Int,
     _ body: (UnsafeMutablePointer<T>) throws -> Result
   ) rethrows -> Result {
     Builtin.bindMemory(_rawValue, count._builtinWordValue, T.self)