build: fix mingw build without sasl

Detected by autogen.sh on a cross-mingw build:

Creating library file: .libs/libvirt.dll.a
Cannot export virNetSASLContextCheckIdentity: symbol not defined
Cannot export virNetSASLContextNewServer: symbol not defined
...

* src/libvirt_private.syms (virnetsaslcontext.h): Move symbols...
* src/libvirt_sasl.syms: ...to new file.
* src/Makefile.am (USED_SYM_FILES) [HAVE_SASL]: Use new file.
(EXTRA_DIST): Ship it.

src/Makefile.am

@@ -1188,18 +1188,23 @@ if WITH_NETWORK
 USED_SYM_FILES += libvirt_network.syms
 endif
 
+if HAVE_SASL
+USED_SYM_FILES += libvirt_sasl.syms
+endif
+
 EXTRA_DIST += \
   libvirt_public.syms		\
   libvirt_private.syms		\
   libvirt_driver_modules.syms	\
   libvirt_bridge.syms		\
+  libvirt_daemon.syms		\
   libvirt_linux.syms		\
   libvirt_macvtap.syms		\
-  libvirt_daemon.syms		\
-  libvirt_nwfilter.syms	\
+  libvirt_network.syms		\
+  libvirt_nwfilter.syms		\
+  libvirt_sasl.syms		\
   libvirt_vmx.syms		\
-  libvirt_xenxs.syms		\
-  libvirt_network.syms
+  libvirt_xenxs.syms
 
 GENERATED_SYM_FILES = libvirt.syms libvirt.def libvirt_qemu.def
 

src/libvirt_private.syms

@@ -1178,20 +1178,6 @@ virNetMessageQueueServe;
 virNetMessageSaveError;
 
 
-# virnetsaslcontext.h
-virNetSASLContextCheckIdentity;
-virNetSASLContextNewServer;
-virNetSASLSessionExtKeySize;
-virNetSASLSessionFree;
-virNetSASLSessionGetIdentity;
-virNetSASLSessionGetKeySize;
-virNetSASLSessionListMechanisms;
-virNetSASLSessionNewServer;
-virNetSASLSessionSecProps;
-virNetSASLSessionServerStart;
-virNetSASLSessionServerStep;
-
-
 # virnetserver.h
 virNetServerAddProgram;
 virNetServerAddService;
@@ -1232,7 +1218,6 @@ virNetServerClientSendMessage;
 virNetServerClientSetCloseHook;
 virNetServerClientSetIdentity;
 virNetServerClientSetPrivateData;
-virNetServerClientSetSASLSession;
 
 
 # virnetserverprogram.h

src/libvirt_sasl.syms

+#
+# SASL-specific symbols
+#
+
+# virnetsaslcontext.h
+virNetSASLContextCheckIdentity;
+virNetSASLContextNewServer;
+virNetSASLSessionExtKeySize;
+virNetSASLSessionFree;
+virNetSASLSessionGetIdentity;
+virNetSASLSessionGetKeySize;
+virNetSASLSessionListMechanisms;
+virNetSASLSessionNewServer;
+virNetSASLSessionSecProps;
+virNetSASLSessionServerStart;
+virNetSASLSessionServerStep;
+
+
+# virnetserverclient.h
+virNetServerClientSetSASLSession;