psmisc: move killall to /usr/libexec and add ALTERNATIVES

Currently, this package can not be installed while using standard path
of busybox, because binary killall wants to be installed on the same
location as busybox.

Collision:
• /usr/bin/killall: busybox (new-file), psmisc (existing-file)

Many of these binaries, which provides alternatives were moved to
folder /usr/libexec like wget, sed, findutils, less.
So I moved killall to /usr/libexec and others leave in touch and added
ALTERNATIVES for it, because preinstall script is no longer necessary.

Signed-off-by: Josef Schlehofer <pepe.schlehofer@gmail.com>
(cherry picked from commit d8969e0f)

utils/psmisc/Makefile

@@ -2,7 +2,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=psmisc
 PKG_VERSION:=23.4
-PKG_RELEASE:=1
+PKG_RELEASE:=2
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.xz
 PKG_SOURCE_URL:=@SF/psmisc
@@ -23,6 +23,7 @@ define Package/psmisc
   TITLE:=proc utilities
   URL:=https://gitlab.com/psmisc/psmisc/
   DEPENDS:=+libncurses
+  ALTERNATIVES:=300:/usr/bin/killall:/usr/libexec/killall
 endef
 
 define Package/psmisc/description
@@ -38,16 +39,11 @@ MAKE_FLAGS += \
 	CPPFLAGS="$(TARGET_CPPFLAGS)" \
 	LDFLAGS="$(TARGET_LDFLAGS)"
 
-define Package/psmisc/preinst
-#!/bin/sh
-if [ -e $${IPKG_INSTROOT}/usr/bin/killall ]; then
-  rm $${IPKG_INSTROOT}/usr/bin/killall;
-fi
-endef
-
 define Package/psmisc/install
 	$(INSTALL_DIR) $(1)/usr/bin
-	$(INSTALL_BIN) $(PKG_INSTALL_DIR)/usr/bin/{fuser,killall,prtstat,pstree} $(1)/usr/bin/
+	$(INSTALL_BIN) $(PKG_INSTALL_DIR)/usr/bin/{fuser,prtstat,pstree} $(1)/usr/bin
+	$(INSTALL_DIR) $(1)/usr/libexec
+	$(INSTALL_BIN) $(PKG_INSTALL_DIR)/usr/bin/killall $(1)/usr/libexec
 endef
 
 $(eval $(call BuildPackage,psmisc))