remove duplicated code
remove duplicated code

- call `UnsafeMutablePointer.allocate(capacity:)` from
  `UnsafeMutableBufferPointer.allocate(capacity:)`.
- This was a straight code duplication.

JGiola/swift,hooman/swift,parkera/swift,hooman/swift,xwu/swift,gregomni/swift,glessard/swift,xwu/swift,JGiola/swift,apple/swift,atrick/swift,JGiola/swift,hooman/swift,roambotics/swift,glessard/swift,ahoppen/swift,ahoppen/swift,rudkx/swift,benlangmuir/swift,hooman/swift,atrick/swift,gregomni/swift,hooman/swift,atrick/swift,tkremenek/swift,hooman/swift,ahoppen/swift,xwu/swift,roambotics/swift,tkremenek/swift,apple/swift,tkremenek/swift,parkera/swift,roambotics/swift,gregomni/swift,rudkx/swift,atrick/swift,glessard/swift,gregomni/swift,glessard/swift,atrick/swift,parkera/swift,benlangmuir/swift,atrick/swift,rudkx/swift,parkera/swift,hooman/swift,xwu/swift,glessard/swift,roambotics/swift,rudkx/swift,glessard/swift,tkremenek/swift,tkremenek/swift,ahoppen/swift,parkera/swift,roambotics/swift,apple/swift,apple/swift,xwu/swift,parkera/swift,apple/swift,JGiola/swift,ahoppen/swift,gregomni/swift,tkremenek/swift,parkera/swift,JGiola/swift,apple/swift,benlangmuir/swift,ahoppen/swift,roambotics/swift,xwu/swift,parkera/swift,rudkx/swift,tkremenek/swift,benlangmuir/swift,JGiola/swift,benlangmuir/swift,rudkx/swift,gregomni/swift,benlangmuir/swift,xwu/swift