use libgcrypt for MD5

This makes sure that CHAP authentication is disabled if the system
is running in FIPS 140-2 mode.  MD5 is not a secure algorithm according
to the standard.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Makefile.am

@@ -34,10 +34,14 @@ dist_noinst_DATA = lib/libiscsi.syms
 lib_LTLIBRARIES = lib/libiscsi.la
 lib_libiscsi_la_SOURCES = \
 	lib/connect.c lib/crc32c.c lib/discovery.c lib/init.c \
-	lib/login.c lib/md5.c lib/nop.c lib/pdu.c lib/iscsi-command.c \
+	lib/login.c lib/nop.c lib/pdu.c lib/iscsi-command.c \
 	lib/scsi-lowlevel.c lib/socket.c lib/sync.c lib/task_mgmt.c \
 	lib/logging.c
 
+if !HAVE_LIBGCRYPT
+lib_libiscsi_la_SOURCES += lib/md5.c
+endif
+
 SONAME=$(firstword $(subst ., ,$(VERSION)))
 SOREL=$(shell printf "%d%02d%02d" $(subst ., ,$(VERSION)))
 lib_libiscsi_la_LDFLAGS = \