CMake 2.8.9 doesn't understand targer_include_directories

To build on older linux distributions, like Debian Wheezy,
the target_include_directories should be replaced with
include_directories.

cmake/BuildZSTD.cmake

@@ -14,7 +14,7 @@ macro(zstd_build)
     set(ZSTD_INCLUDE_DIRS
             ${CMAKE_CURRENT_SOURCE_DIR}/third_party/zstd/lib
             ${CMAKE_CURRENT_SOURCE_DIR}/third_party/zstd/lib/common)
-    target_include_directories(zstd PUBLIC ${ZSTD_INCLUDE_DIRS})
+    include_directories(${ZSTD_INCLUDE_DIRS})
     find_package_message(ZSTD "Using bundled ZSTD"
         "${ZSTD_LIBRARIES}:${ZSTD_INCLUDE_DIRS}")
     add_dependencies(build_bundled_libs zstd)