libnm: move nm-errors.h include away from nm-connection.h

Most users included this by accident, by including nm-connection.h. That
is not too great, becuase stuff it contains is by no means specific to
NMConnection.

Anyways, it's not like it would matter too that. I mainly care about it
being included in NetworkManager.h, so that there's one less special
case in a test that makes sure useful stuff from NetworkManager.h ends up
in gtk-doc (a separate commit).

src/core/nm-default-daemon.h

@@ -18,6 +18,7 @@
 #include "nm-version.h"
 
 #include "nm-core-types.h"
+#include "nm-errors.h"
 #include "nm-types.h"
 #include "libnm-log-core/nm-logging.h"
 

src/libnm-client-impl/nm-default-libnm.h

@@ -27,6 +27,7 @@
 #include "nm-client.h"
 #include "nm-vpn-connection.h"
 #include "nm-libnm-utils.h"
+#include "nm-errors.h"
 
 /*****************************************************************************/
 

src/libnm-client-public/NetworkManager.h

@@ -15,6 +15,8 @@
 
 #include "nm-core-enum-types.h"
 
+#include "nm-errors.h"
+
 #include "nm-connection.h"
 #include "nm-simple-connection.h"
 #include "nm-keyfile.h"

src/libnm-core-impl/nm-default-libnm-core.h

@@ -16,6 +16,7 @@
 /*****************************************************************************/
 
 #include "nm-version.h"
+#include "nm-errors.h"
 
 /*****************************************************************************/
 

src/libnm-core-public/nm-connection.h

@@ -13,7 +13,6 @@
 
 #include "nm-core-types.h"
 #include "nm-setting.h"
-#include "nm-errors.h"
 
 G_BEGIN_DECLS