linker warnings on macOS/Clang fixed

CMakeLists.txt

@@ -68,11 +68,14 @@ elseif (${CMAKE_CXX_COMPILER_ID} MATCHES "Clang")
     add_compile_options (-Warray-bounds)
     # Increase template depth for boost
     add_compile_options (-ftemplate-depth=1024)
+    add_compile_options (-fvisibility=hidden)
+    add_compile_options (-fvisibility-inlines-hidden)
     # Allow overloaded virtual functions (instances to be fixed in OPAL)
     #add_compile_options (-Wno-overloaded-virtual)
     if (ENABLE_OpenMP)
 	    add_compile_options (-fopenmp)
     endif ()
+    add_link_options (-Wl,-no_compact_unwind)
 
 elseif (${CMAKE_CXX_COMPILER_ID} MATCHES "GNU")
     if (${CMAKE_CXX_COMPILER_VERSION} VERSION_LESS "4.7.3")