liblog: __android_logger_property_bool svelte+eng default

When BOOL_DEFAULT_FLAG_ENG and/or BOOL_DEFAULT_FLAG_SVELTE is set for
flags parameter in __android_logger_property_get_bool, they can not be
overridden by a supplied property value.  Reset these two flags if
there is something in the specified property.

Test: gTest liblog-unit-tests, logcat-unit-tests and logd-unit-tests
Bug: 37425809
Change-Id: I5fc2d727e8c30bc1e781f8b365f44ec62dd36b4d