Work around vs2013sp2-3 bug in skstd::unique_ptr.

When compiling skstd::unique_ptr::compressed_base with the vc++ in
some intermediate service pack versions of Visual Studio 2013 the
compiler will crash with an internal compiler error. In the interest of
reducing headaches, work around this issue in skstd::unique_ptr until
std::unique_ptr can be used.

BUG=skia:4564

Review URL: https://codereview.chromium.org/1636503002
1 file changed