lmbench: fix doc install failure

Fix the failure:
cp: cannot create regular file `/usr/share/man/man1/bargraph.1': Permission denied
mkdir: cannot create directory `/usr/share/man/man9': Permission denied

Signed-off-by: Jackie Huang <jackie.huang@windriver.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>

meta-oe/recipes-benchmark/lmbench/lmbench_3.0-a9.bb

@@ -52,7 +52,7 @@ do_install () {
               > ${D}${sysconfdir}/tmpfiles.d/lmbench.conf
     fi
 
-    oe_runmake 'BASE=${D}${prefix}' \
+    oe_runmake BASE="${D}${prefix}" MANDIR="${D}${mandir}" \
             -C src install
     mv ${D}${bindir}/line ${D}${bindir}/lm_line
     install -m 0755 ${WORKDIR}/lmbench-run ${D}${bindir}/