at: Use variables from the environment to override the makefile defaults

This allows us to remove the docdir worksarounds and fixes other
potential relocation issues at the same time as cleaning up the
recipe.

(From OE-Core rev: 3be575babcdb12f95f4882d3c42bdf3ba1ec1900)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-extended/at/at_3.1.13.bb

@@ -11,7 +11,7 @@ PAM_DEPS = "libpam libpam-runtime pam-plugin-env pam-plugin-limits"
 
 RCONFLICTS_${PN} = "atd"
 RREPLACES_${PN} = "atd"
-PR = "r1"
+PR = "r2"
 
 SRC_URI = "${DEBIAN_MIRROR}/main/a/at/at_${PV}.orig.tar.gz \
     file://configure.patch \
@@ -45,14 +45,12 @@ do_compile_prepend () {
 }
 
 do_install () {
-	oe_runmake "IROOT=${D}" install
+	oe_runmake -e "IROOT=${D}" install
 
 	install -d ${D}${sysconfdir}/init.d
 	install -d ${D}${sysconfdir}/rcS.d
 	install -m 0755    ${WORKDIR}/S99at		${D}${sysconfdir}/init.d/atd
 	ln -sf ../init.d/atd ${D}${sysconfdir}/rcS.d/S99at
-	cp -r ${D}/usr/doc/at ${D}${docdir}/
-	rm -rf ${D}/usr/doc
 
 	for feature in ${DISTRO_FEATURES}; do
 		if [ "$feature" = "pam" ]; then