It is obviously configure deps error

[Douglas Mencken]

After I switched off 'pmap' applet (which is already included in
procps package):

@@ -860,7 +860,7 @@
 #
 CONFIG_IOSTAT=y
 # CONFIG_MPSTAT is not set
-CONFIG_PMAP=y
+# CONFIG_PMAP is not set
 # CONFIG_SMEMCAP is not set
 # CONFIG_FREE is not set
 CONFIG_FUSER=y

everything builds just fine. I have working busybox. But this is
obviously a bug in configure dependencies.