Utilities/Release: Update for using Windows 10 SDK

In commit e903a9fc (Utilities/Release: Create a Windows 64-bit binary,
2016-03-16, v3.6.0-rc1~235^2~2) we added a `_USING_V110_SDK71_` macro to
tell the MSVC standard library headers they were using an older SDK.
The environment in which our Windows binaries are produced has been
updated to use a Windows 10 SDK now that we do not need to support
WinXP, so we can drop the definition.

Utilities/Release/win32_release.cmake

@@ -31,7 +31,7 @@ CMAKE_PREFIX_PATH:STRING=${qt_prefix}
 CMake_TEST_Qt4:BOOL=OFF
 CMake_TEST_Qt5:BOOL=OFF
 ")
-set(ppflags "-D_WIN32_WINNT=0x601 -DNTDDI_VERSION=0x06010000 -D_USING_V110_SDK71_")
+set(ppflags "-D_WIN32_WINNT=0x601 -DNTDDI_VERSION=0x06010000")
 set(CFLAGS "${ppflags}")
 set(CXXFLAGS "${ppflags}")
 set(ENV ". ~/rel/env32")

Utilities/Release/win64_release.cmake

@@ -31,7 +31,7 @@ CMAKE_PREFIX_PATH:STRING=${qt_prefix}
 CMake_TEST_Qt4:BOOL=OFF
 CMake_TEST_Qt5:BOOL=OFF
 ")
-set(ppflags "-D_WIN32_WINNT=0x601 -DNTDDI_VERSION=0x06010000 -D_USING_V110_SDK71_")
+set(ppflags "-D_WIN32_WINNT=0x601 -DNTDDI_VERSION=0x06010000")
 set(CFLAGS "${ppflags}")
 set(CXXFLAGS "${ppflags}")
 set(ENV ". ~/rel/env64")