File contains helpful variabls for portfiles which are commonly needed or used.
VCPKG_TARGET_IS_<target> with <target> being one of the following: WINDOWS, UWP, LINUX, OSX, ANDROID, FREEBSD. only defined if <target>
VCPKG_TARGET_STATIC_LIBRARY_PREFIX static library prefix for target (same as CMAKE_STATIC_LIBRARY_PREFIX)
VCPKG_TARGET_STATIC_LIBRARY_SUFFIX static library suffix for target (same as CMAKE_STATIC_LIBRARY_SUFFIX)
VCPKG_TARGET_SHARED_LIBRARY_PREFIX shared library prefix for target (same as CMAKE_SHARED_LIBRARY_PREFIX)
VCPKG_TARGET_SHARED_LIBRARY_SUFFIX shared library suffix for target (same as CMAKE_SHARED_LIBRARY_SUFFIX)
CMAKE_STATIC_LIBRARY_PREFIX, CMAKE_STATIC_LIBRARY_SUFFIX, CMAKE_SHARED_LIBRARY_PREFIX, CMAKE_SHARED_LIBRARY_SUFFIX are defined for the target so that portfiles are able to use find_library calls to discover dependent libraries within the current triplet for ports.