Fetcher: break the "SRCREVINACTION" deadlock

Current fetcher has annoying "SRCREVINACTION" deadlock,
which occurs when SRCREV=${AUTOREV}=@bb.fetch.get_srcrev():
get_srcrev()->setup_localpath()->srcrev_internal_helper()
->evaluate SRCREV->get_srcrev()

current fetcher resolve the deadlock by introducing a
"SRCREVINACTION" condition check. Althoguh it works, it is
indeed not clean.

This patch use antoehr idea to break the deadlock: break
the dependency among SRCREV and get_srcrev(), i.e. assign
a specific keyword "AUTOINC" to AUTOREV. when Fetcher meet
this keyword, it will check and set the latest revision to
urldata.revision. get_srcrev later can use the urldata.revision
for value evaluation(SRCPV etc). In this case, SRCREV no longer
depends on get_srcrev, and there is not deadlock anymore.

Signed-off-by: Yu Ke <ke.yu@intel.com>

meta/conf/bitbake.conf

@@ -537,7 +537,7 @@ UPDATECOMMAND_cvs = "/usr/bin/env cvs -d${CVSROOT} update -d -P ${CVSCOOPTS}"
 UPDATECOMMAND_svn = "/usr/bin/env svn update ${SVNCOOPTS}"
 SRCDATE = "${DATE}"
 SRCREV = "INVALID"
-AUTOREV = "${SRCPV}"
+AUTOREV = "${@bb.fetch.get_autorev(d)}"
 SRCPV = "${@bb.fetch.get_srcrev(d)}"
 
 SRC_URI = "file://${FILE}"