return to using replaceAllUsesWith

refs #101
C++ constructors should be appended to _plugin_ctors, not __shadow_plugin_init__

Signed-off-by: Andrew Miller <amiller@dappervision.com>
calling fcntl(FSET_FL) and fcntl(FGET_FL) on a descriptor now return something meaningful

Signed-off-by: Andrew Miller <amiller@dappervision.com>
Merge branch 'master' of github.com:amiller/shadow