[cmake] Remove HB_DISABLE_DEPRECATED as it seems needed for pango build (#470)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index a43857e..2c03f2b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -36,9 +36,7 @@
   ${PROJECT_BINARY_DIR}/src
   )
 
-# feel free to discuss these or more with the maintainers
 add_definitions(-DHAVE_OT)
-add_definitions(-DHB_DISABLE_DEPRECATED)
 
 if (BUILD_SHARED_LIBS)
   add_definitions(-DHAVE_ATEXIT)