lzip: clean up recipe

Use cleandirs to ensure ${B} is always empty, and remove redundant assignment of
EXTRA_OEMAKE (presumably from when it had a non-empty default).

(From OE-Core rev: 326e183479f9cae12f2219a2bf9112b322832daa)

Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-extended/lzip/lzip_1.20.bb

@@ -6,10 +6,12 @@ LIC_FILES_CHKSUM = "file://COPYING;md5=76d6e300ffd8fb9d18bd9b136a9bba13 \
                     file://decoder.cc;beginline=3;endline=16;md5=db09fe3f9573f94d0076f7f07959e6e1"
 
 SRC_URI = "${SAVANNAH_GNU_MIRROR}/lzip/lzip-${PV}.tar.gz"
-
 SRC_URI[md5sum] = "21c1517da2ace9689fd953918660b3c3"
 SRC_URI[sha256sum] = "c93b81a5a7788ef5812423d311345ba5d3bd4f5ebf1f693911e3a13553c1290c"
 
+B = "${WORKDIR}/build"
+do_configure[cleandirs] = "${B}"
+
 CONFIGUREOPTS = "\
     '--srcdir=${S}' \
     '--prefix=${prefix}' \
@@ -23,9 +25,7 @@ CONFIGUREOPTS = "\
     'CXXFLAGS=${CXXFLAGS}' \
     'LDFLAGS=${LDFLAGS}' \
 "
-EXTRA_OEMAKE = ""
 
-B = "${S}/obj"
 do_configure () {
     ${S}/configure ${CONFIGUREOPTS}
 }