Added flags parameter to register_property method

- flags parameter is set by default to vtable::property_::emits_change
- with this change user can set parameter to vtable::property_::none
  to avoid sending property change signal for greater performance
- added example/register-property.cpp with example application
  which uses new functions

Tested:
- run openbmc tests with this change, no regression detected
- tested that default behaviour (property_::emits_change) is working as intended
- tested that properties still signal change when emit_change flag is used
- tested that properties doesn't signal change when no emit_change flag is used
- tested that const flag is passed and handled corretly
- verified that performance of application increases when emit_change flag turned off

Signed-off-by: Krzysztof Grobelny <krzysztof.grobelny@intel.com>
Change-Id: If6187cf076b8e05a5211c83797374a3be94da0c9
diff --git a/example/meson.build b/example/meson.build
index 957c01d..aed2a33 100644
--- a/example/meson.build
+++ b/example/meson.build
@@ -22,6 +22,19 @@
     dependencies: [ boost_dep, sdbusplus_dep ],
 )
 
+executable(
+    'register-property',
+    'register-property.cpp',
+    cpp_args: [
+        '-DBOOST_ASIO_DISABLE_THREADS',
+        '-DBOOST_ALL_NO_LIB',
+        '-DBOOST_SYSTEM_NO_DEPRECATED',
+        '-DBOOST_ERROR_CODE_HEADER_ONLY',
+        '-DBOOST_COROUTINES_NO_DEPRECATION_WARNING',
+    ],
+    dependencies: [ boost_dep, sdbusplus_dep ],
+)
+
 calc_buildroot = meson.current_build_dir()
 calc_files = files(
     run_command(