We no longer use predefined _DLL, which can be defined for static
builds too with /MD. We use DLL_EXPORT and DLL_IMPORT instead,
following libtool convention.
* CMakeLists.txt [WIN32], builds/windows/vc2010/freetype.vcxproj:
Define DLL_EXPORT manually.
* include/freetype/config/ftconfig.h, builds/unix/ftconfig.in,
builds/vms/ftconfig.h, builds/windows/vc2010/index.html,
src/base/ftver.rc: /_DLL/d, s/FT2_DLLIMPORT/DLL_IMPORT/.