Add InMon's sFlow Agent library to the build system.

The C source and header files added in this commit is covered under the
InMon sFlow license at http://www.inmon.com/technology/sflowlicense.txt

The library requires -Wno-unused to compile without warnings, so this
commit adds that for building the sFlow code only.  Automake can only
change compiler flags on a per-library or per-program basis, so sFlow
is built as a separate library.

The library will be used in upcoming commits.

COPYING

@@ -22,3 +22,7 @@ Public License, version 2.
 Files under the xenserver directory are licensed on a file-by-file
 basis.  Some files are under an uncertain license that may not be
 DFSG-compliant or GPL-compatible.  Refer to each file for details.
+
+Files lib/sflow*.[ch] are licensed under the terms of the InMon sFlow
+licence that is available at:
+        http://www.inmon.com/technology/sflowlicense.txt

acinclude.m4

@@ -235,4 +235,14 @@ dnl Example: OVS_ENABLE_OPTION([-Wdeclaration-after-statement])
 AC_DEFUN([OVS_ENABLE_OPTION], 
   [OVS_CHECK_CC_OPTION([$1], [WARNING_FLAGS="$WARNING_FLAGS $1"])
    AC_SUBST([WARNING_FLAGS])])
+
+dnl OVS_CONDITIONAL_CC_OPTION([OPTION], [CONDITIONAL])
+dnl Check whether the given C compiler OPTION is accepted.
+dnl If so, enable the given Automake CONDITIONAL.
+
+dnl Example: OVS_CONDITIONAL_CC_OPTION([-Wno-unused], [HAVE_WNO_UNUSED])
+AC_DEFUN([OVS_CONDITIONAL_CC_OPTION],
+  [OVS_CHECK_CC_OPTION(
+    [$1], [ovs_have_cc_option=yes], [ovs_have_cc_option=no])
+   AM_CONDITIONAL([$2], [test $ovs_have_cc_option = yes])])
 dnl ----------------------------------------------------------------------

configure.ac

@@ -75,6 +75,7 @@ OVS_ENABLE_OPTION([-Wold-style-definition])
 OVS_ENABLE_OPTION([-Wmissing-prototypes])
 OVS_ENABLE_OPTION([-Wmissing-field-initializers])
 OVS_ENABLE_OPTION([-Wno-override-init])
+OVS_CONDITIONAL_CC_OPTION([-Wno-unused], [HAVE_WNO_UNUSED])
 
 AC_ARG_VAR(KARCH, [Kernel Architecture String])
 AC_SUBST(KARCH)

lib/automake.mk

@@ -125,6 +125,19 @@ nodist_lib_libopenvswitch_a_SOURCES = \
 	lib/dirs.c
 CLEANFILES += $(nodist_lib_libopenvswitch_a_SOURCES)
 
+noinst_LIBRARIES += lib/libsflow.a
+lib_libsflow_a_SOURCES = \
+	lib/sflow_api.h \
+	lib/sflow.h \
+	lib/sflow_agent.c \
+	lib/sflow_sampler.c \
+	lib/sflow_poller.c \
+	lib/sflow_receiver.c
+lib_libsflow_a_CFLAGS = $(AM_CFLAGS)
+if HAVE_WNO_UNUSED
+lib_libsflow_a_CFLAGS += -Wno-unused
+endif
+
 if HAVE_NETLINK
 lib_libopenvswitch_a_SOURCES += \
 	lib/netlink-protocol.h \