HDFS-7385. ThreadLocal used in FSEditLog class causes FSImage permission mess up. Contributed by jiangyu.

(cherry picked from commit b0a41de68c5b08f534ca231293de053c0b0cbd5d)
(cherry picked from commit 4e9001530f7bc414b43723858cf7984f707b30e0)
(cherry picked from commit ed2a4db6d4dbb1e0a2d589dda9cdea281e8e5d39)
Preparing to release hadoop-2.6.0-rc1.

(cherry picked from commit 9ff7315cbe9804bebcd1ec093fac7828a72ddf59)

Conflicts:
	hadoop-common-project/hadoop-common/CHANGES.txt
	hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
	hadoop-mapreduce-project/CHANGES.txt
	hadoop-yarn-project/CHANGES.txt

(cherry picked from commit 98a4538cf4b4fd87409fe364487825a4f9df2872)