add --with-tweetnacl to configure

allows building with tweetnacl without cmake

Makefile.am

@@ -274,6 +274,15 @@ src_libzmq_la_CPPFLAGS += ${sodium_CFLAGS}
 src_libzmq_la_LIBADD += ${sodium_LIBS}
 endif
 
+if USE_TWEETNACL
+src_libzmq_la_SOURCES += \
+    tweetnacl/src/tweetnacl.c \
+    tweetnacl/contrib/randombytes/devurandom.c
+src_libzmq_la_CXXFLAGS += \
+    -I$(top_builddir)/tweetnacl/contrib/randombytes \
+    -I$(top_builddir)/tweetnacl/src
+endif
+
 if HAVE_PGM
 src_libzmq_la_CPPFLAGS += ${pgm_CFLAGS}
 src_libzmq_la_LIBADD += ${pgm_LIBS}

configure.ac

@@ -431,6 +431,12 @@ AC_ARG_WITH([libsodium], [AS_HELP_STRING([--with-libsodium],
     [require_libsodium_ext=$withval],
     [require_libsodium_ext=yes])
 
+AC_ARG_WITH([tweetnacl], [AS_HELP_STRING([--with-tweetnacl],
+    [build libzmq  with bundled tweetnacl crypto library [default=no]])],
+    [require_libsodium_ext=no
+     with_tweetnacl=yes],
+    [with_tweetnacl=no])
+
 # conditionally require libsodium package
 if test "x$require_libsodium_ext" != "xno"; then
     PKG_CHECK_MODULES([sodium], [libsodium], [have_sodium_library="yes"])
@@ -446,10 +452,14 @@ if test "x$have_sodium_library" != "xno"; then
             CPPFLAGS="$CPPFLAGS -Wno-long-long"
         ;;
     esac
+elif test "x$with_tweetnacl" != "xno"; then
+    echo "using tweetnacl"
+    AC_DEFINE(HAVE_LIBSODIUM, 1, [Sodium is provided by tweetnacl.])
+    AC_DEFINE(HAVE_TWEETNACL, 1, [Using tweetnacl.])
 fi
 
-
 AM_CONDITIONAL(HAVE_SODIUM, test "x$have_sodium_library" != "xno")
+AM_CONDITIONAL(USE_TWEETNACL, test "x$with_tweetnacl" != "xno")
 
 # build using pgm
 have_pgm_library="no"