Resolve a few Data warnings (#1583)

Author: jmschonfeld

Sources/FoundationEssentials/Data/DataProtocol.swift

@@ -239,7 +239,9 @@ extension Data : MutableDataProtocol {
     public var regions: CollectionOfOne<Data> {
         return CollectionOfOne(self)
     }
-    
+}
+
+extension Data {
     /// Copy the contents of the data to a pointer.
     ///
     /// - parameter pointer: A pointer to the buffer you wish to copy the bytes into.

Sources/FoundationEssentials/Data/Representations/Data+LargeSlice.swift

@@ -159,7 +159,6 @@ extension Data {
         @inlinable // This is @inlinable as reasonably small.
         mutating func append(contentsOf buffer: UnsafeRawBufferPointer) {
             ensureUniqueReference()
-            let upperbound = storage.length + storage._offset
             storage.replaceBytes(
                 in: (
                     location: range.upperBound,