Replace include statements with require

None of them express optional inclusions. This change is primarily to
document correct use.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>

meta-isar/recipes-core/images/isar-image-debug.bb

@@ -3,7 +3,7 @@
 # This software is a part of ISAR.
 # Copyright (C) 2015-2016 ilbers GmbH
 
-include recipes-core/images/isar-image-base.bb
+require recipes-core/images/isar-image-base.bb
 
 IMAGE_PREINSTALL += "gdb \
                      strace"

meta-isar/recipes-kernel/example-module/example-module.bb

@@ -15,7 +15,7 @@ python() {
         d.setVar('ISAR_CROSS_COMPILE', '0')
 }
 
-include recipes-kernel/linux-module/module.inc
+require recipes-kernel/linux-module/module.inc
 
 SRC_URI += "file://src"
 

meta/recipes-core/isar-bootstrap/isar-bootstrap-host.bb

@@ -11,7 +11,7 @@ WORKDIR = "${TMPDIR}/work/${DISTRO}-${DISTRO_ARCH}/${PN}-${HOST_DISTRO}-${HOST_A
 DEPLOY_ISAR_BOOTSTRAP = "${DEPLOY_DIR_BOOTSTRAP}/${HOST_DISTRO}-${HOST_ARCH}"
 ISAR_BOOTSTRAP_LOCK = "${DEPLOY_DIR_BOOTSTRAP}/${HOST_DISTRO}-${HOST_ARCH}.lock"
 
-include isar-bootstrap.inc
+require isar-bootstrap.inc
 inherit isar-bootstrap-helper
 
 do_generate_keyring[stamp-extra-info] = "${DISTRO}-${DISTRO_ARCH}"

meta/recipes-core/isar-bootstrap/isar-bootstrap-target.bb

@@ -11,7 +11,7 @@ WORKDIR = "${TMPDIR}/work/${DISTRO}-${DISTRO_ARCH}/${PN}"
 DEPLOY_ISAR_BOOTSTRAP = "${DEPLOY_DIR_BOOTSTRAP}/${DISTRO}-${DISTRO_ARCH}"
 ISAR_BOOTSTRAP_LOCK = "${DEPLOY_DIR_BOOTSTRAP}/${DISTRO}-${DISTRO_ARCH}.lock"
 
-include isar-bootstrap.inc
+require isar-bootstrap.inc
 
 do_generate_keyring[stamp-extra-info] = "${DISTRO}-${DISTRO_ARCH}"
 

meta/recipes-devtools/buildchroot/buildchroot-host.bb

@@ -5,7 +5,7 @@
 
 DESCRIPTION = "Isar development filesystem for host"
 
-include buildchroot.inc
+require buildchroot.inc
 
 BUILDCHROOT_PREINSTALL ?= "make \
                            debhelper \

meta/recipes-devtools/buildchroot/buildchroot-target.bb

@@ -5,7 +5,7 @@
 
 DESCRIPTION = "Isar development filesystem for target"
 
-include buildchroot.inc
+require buildchroot.inc
 
 BUILDCHROOT_PREINSTALL ?= "gcc \
                            make \