package/finit: add support for BR2_ROOTFS_MERGED_USR

Ensure Finit installs its files to /usr/lib/finit when building with the
merged-usr config option.  For consistency we adjust --exec-prefix, which
is the base for $libdir, meaning also /libexec is moved to /usr/libexec.

Finit tracks the paths internally, we only need to update runparts probe.

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

board/common/rootfs/etc/finit.d/10-infix.conf

@@ -1 +1,3 @@
-task name:ixinit log:tag:ixinit [S] <pid/syslogd> /libexec/finit/runparts -bp /libexec/infix/init.d -- Probing system
+task name:ixinit log:tag:ixinit [S] <pid/syslogd> \
+	/usr/libexec/finit/runparts -bp /libexec/infix/init.d \
+	-- Probing system

package/finit/finit.mk

@@ -27,13 +27,18 @@ FINIT_D = $(TARGET_DIR)/etc/finit.d
 # no override necessary there.
 FINIT_CONF_OPTS =					\
 	--prefix=/usr					\
-	--exec-prefix=					\
 	--disable-doc					\
 	--disable-contrib				\
 	--disable-rescue				\
 	--disable-silent-rules				\
 	--with-group=$(BR2_PACKAGE_FINIT_INITCTL_GROUP)
 
+ifeq ($(BR2_ROOTFS_MERGED_USR),y)
+FINIT_CONF_OPTS += --exec-prefix=/usr
+else
+FINIT_CONF_OPTS += --exec-prefix=
+endif
+
 ifeq ($(BR2_PACKAGE_FINIT_ADVANCED),y)
 ifneq ($(BR2_PACKAGE_FINIT_CUSTOM_FSTAB),)
 FINIT_CONF_OPTS += --with-fstab=$(BR2_PACKAGE_FINIT_CUSTOM_FSTAB)