package/udpcast: fix build without pod2man

udpcast unconditionally build manpages which will raise the following
build failure without pod2man since at least bump to version 20200328 in
commit 4fb91d8b9dff314fc53438144f843b3e3ceaacaa:

sh: line 1: pod2man: command not found

To fix this issue, rework how udpcast is built and installed to always
build and install the sender or the receiver and never build the
manpages. As a side effect, this will also avoid to install the unneeded
rateGovernor.h

Fixes:
 - http://autobuild.buildroot.org/results/ce602a09357e950d79794391cd4a852d565914f1

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
(cherry picked from commit b49e3da1abf3a6c8affac08089311fc6590f54d0)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/udpcast/Config.in

@@ -6,6 +6,8 @@ config BR2_PACKAGE_UDPCAST
 	bool "udpcast"
 	depends on BR2_TOOLCHAIN_HAS_THREADS
 	depends on BR2_USE_MMU # fork()
+	select BR2_PACKAGE_UDPCAST_SENDER \
+		if !BR2_PACKAGE_UDPCAST_RECEIVER
 	help
 	  A multicast protocol implementation which happens to
 	  be very handy for imaging drives over the network.

package/udpcast/udpcast.mk

@@ -9,23 +9,15 @@ UDPCAST_SITE = http://www.udpcast.linux.lu/download
 UDPCAST_DEPENDENCIES = host-m4
 UDPCAST_LICENSE = BSD-2-Clause, GPL-2.0+
 UDPCAST_LICENSE_FILES = COPYING
+UDPCAST_TARGETS = \
+	$(if $(BR2_PACKAGE_UDPCAST_RECEIVER),udp-receiver) \
+	$(if $(BR2_PACKAGE_UDPCAST_SENDER),udp-sender)
+UDPCAST_MAKE_OPTS = $(UDPCAST_TARGETS)
 
-define UDPCAST_REMOVE_UDP_SENDER
-	rm -f $(TARGET_DIR)/usr/sbin/udp-sender
-	rm -f $(TARGET_DIR)/usr/sbin/udp-sender.1
+define UDPCAST_INSTALL_TARGET_CMDS
+	$(foreach f,$(UDPCAST_TARGETS),\
+		$(INSTALL) -D -m 755 $(@D)/$(f) $(TARGET_DIR)/usr/sbin/$(f)
+	)
 endef
 
-ifneq ($(BR2_PACKAGE_UDPCAST_SENDER),y)
-UDPCAST_POST_INSTALL_TARGET_HOOKS += UDPCAST_REMOVE_UDP_SENDER
-endif
-
-define UDPCAST_REMOVE_UDP_RECEIVER
-	rm -f $(TARGET_DIR)/usr/sbin/udp-receiver
-	rm -f $(TARGET_DIR)/usr/sbin/udp-receiver.1
-endef
-
-ifneq ($(BR2_PACKAGE_UDPCAST_RECEIVER),y)
-UDPCAST_POST_INSTALL_TARGET_HOOKS += UDPCAST_REMOVE_UDP_RECEIVER
-endif
-
 $(eval $(autotools-package))