gss: SAnon - the Simple Anonymous GSS-API mechanism

Add support for SAnon, a simple key agreement protocol that provides no
authentication of initiator or acceptor using x25519 ECDH key exchange.
See doc/standardization/draft-howard-gss-sanon-xx.txt for a protocol
description.

lib/gssapi/Makefile.am

@@ -12,6 +12,7 @@ AM_CPPFLAGS += \
 	-I$(srcdir)/ntlm \
 	-I$(srcdir)/krb5 \
 	-I$(srcdir)/spnego \
+	-I$(srcdir)/sanon \
 	$(INCLUDE_libintl)
 
 lib_LTLIBRARIES = libgssapi.la test_negoex_mech.la
@@ -215,11 +216,45 @@ ntlmsrc = \
 $(srcdir)/ntlm/ntlm-private.h: $(ntlmsrc)
 	cd $(srcdir) && perl ../../cf/make-proto.pl -q -P comment -p ntlm/ntlm-private.h $(ntlmsrc) || rm -f ntlm/ntlm-private.h
 
+sanonsrc = \
+	sanon/accept_sec_context.c \
+	sanon/acquire_cred.c \
+	sanon/add_cred.c \
+	sanon/canonicalize_name.c \
+	sanon/compare_name.c \
+	sanon/context_time.c \
+	sanon/crypto.c \
+	sanon/delete_sec_context.c \
+	sanon/display_name.c \
+	sanon/display_status.c \
+	sanon/duplicate_cred.c \
+	sanon/duplicate_name.c \
+	sanon/export_name.c \
+	sanon/export_cred.c \
+	sanon/export_sec_context.c \
+	sanon/external.c \
+	sanon/import_cred.c \
+	sanon/import_name.c \
+	sanon/import_sec_context.c \
+	sanon/init_sec_context.c \
+	sanon/inquire_context.c \
+	sanon/inquire_cred.c \
+	sanon/inquire_cred_by_mech.c \
+	sanon/inquire_mechs_for_name.c \
+	sanon/inquire_names_for_mech.c \
+	sanon/inquire_sec_context_by_oid.c \
+	sanon/negoex.c \
+	sanon/process_context_token.c \
+	sanon/release_cred.c \
+	sanon/release_name.c \
+	sanon/sanon-private.h
+
 dist_libgssapi_la_SOURCES  = \
 	$(krb5src) \
 	$(mechsrc) \
 	$(ntlmsrc) \
-	$(spnegosrc)
+	$(spnegosrc) \
+	$(sanonsrc)
 
 nodist_libgssapi_la_SOURCES  = \
 	gkrb5_err.c \
@@ -252,6 +287,7 @@ noinst_HEADERS = \
 	gssapi_mech.h \
 	$(srcdir)/ntlm/ntlm-private.h \
 	$(srcdir)/spnego/spnego-private.h \
+	$(srcdir)/sanon/sanon-private.h \
 	$(srcdir)/krb5/gsskrb5-private.h
 
 nobase_include_HEADERS = \
@@ -281,6 +317,7 @@ spnego_files =					\
 BUILTHEADERS = \
 	$(srcdir)/krb5/gsskrb5-private.h \
 	$(srcdir)/spnego/spnego-private.h \
+	$(srcdir)/sanon/sanon-private.h \
 	$(srcdir)/ntlm/ntlm-private.h
 
 $(libgssapi_la_OBJECTS): $(BUILTHEADERS)
@@ -315,6 +352,8 @@ $(srcdir)/krb5/gsskrb5-private.h:
 $(srcdir)/spnego/spnego-private.h:
 	cd $(srcdir) && perl ../../cf/make-proto.pl -q -P comment -p spnego/spnego-private.h $(spnegosrc) || rm -f spnego/spnego-private.h
 
+$(srcdir)/sanon/sanon-private.h:
+	cd $(srcdir) && perl ../../cf/make-proto.pl -q -P comment -p sanon/sanon-private.h $(sanonsrc) || rm -f sanon/sanon-private.h
 
 TESTS = test_oid test_names test_cfx
 # test_sequence