Enable implicit symbol hiding for all libraries, static and shared

This covers all built libraries now and both static and shared builds.

CMakeLists.txt

 cmake_minimum_required(VERSION 2.8.0)
+# Allow symbol hiding for both static and shared libs.
+cmake_policy(SET CMP0063 NEW)
+
 project(harfbuzz)
 
 enable_testing()
@@ -524,23 +527,19 @@ endif ()
 
 ## Define harfbuzz library
 add_library(harfbuzz ${project_sources} ${project_extra_sources} ${project_headers})
-target_link_libraries(harfbuzz ${THIRD_PARTY_LIBS})
-
-if (BUILD_SHARED_LIBS)
-  if (WIN32 AND NOT MINGW)
-    add_definitions("-DHB_EXTERN=__declspec(dllexport) extern")
-  else ()
-    add_definitions("-DHB_EXTERN=__attribute__(( visibility( \"default\" ) )) extern")
-    set_target_properties(harfbuzz PROPERTIES
+set_target_properties(harfbuzz PROPERTIES
   C_VISIBILITY_PRESET hidden
   CXX_VISIBILITY_PRESET hidden
   VISIBILITY_INLINES_HIDDEN TRUE)
-  endif ()
-endif ()
+target_link_libraries(harfbuzz ${THIRD_PARTY_LIBS})
 
 ## Define harfbuzz-subset library
 add_library(harfbuzz-subset ${subset_project_sources} ${subset_project_headers})
 add_dependencies(harfbuzz-subset harfbuzz)
+set_target_properties(harfbuzz-subset PROPERTIES
+  C_VISIBILITY_PRESET hidden
+  CXX_VISIBILITY_PRESET hidden
+  VISIBILITY_INLINES_HIDDEN TRUE)
 target_link_libraries(harfbuzz-subset harfbuzz ${THIRD_PARTY_LIBS})
 
 if (UNIX OR MINGW)
@@ -568,11 +567,23 @@ if (HB_HAVE_GOBJECT)
     ${hb_gobject_headers}
     ${hb_gobject_gen_headers}
   )
+  set_target_properties(harfbuzz-gobject PROPERTIES
+    C_VISIBILITY_PRESET hidden
+    CXX_VISIBILITY_PRESET hidden
+    VISIBILITY_INLINES_HIDDEN TRUE)
   include_directories(BEFORE ${CMAKE_CURRENT_BINARY_DIR}/src)
   add_dependencies(harfbuzz-gobject harfbuzz)
   target_link_libraries(harfbuzz-gobject harfbuzz ${GOBJECT_LIBRARIES} ${THIRD_PARTY_LIBS})
 endif ()
 
+if (BUILD_SHARED_LIBS)
+  if (WIN32 AND NOT MINGW)
+    add_definitions("-DHB_EXTERN=__declspec(dllexport) extern")
+  else ()
+    add_definitions("-DHB_EXTERN=__attribute__(( visibility( \"default\" ) )) extern")
+  endif ()
+endif ()
+
 # On Windows, g-ir-scanner requires a DLL build in order for it to work
 if (WIN32)
   if (NOT BUILD_SHARED_LIBS)