man-pages: upgrade 6.06 -> 6.8

* drop 0001-man.ml-do-not-use-dev-stdin.patch since upstream already fix
the issue, refer [1]

* drop 0001-GNUmakefile-use-env-from-PATH.patch since upstream already
fix the issue, refer [2], and drop depends on coreutils-native

[1] https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/commit/share/mk/install/man.mk?id=9524f0f63badd896ccf6da7d79511100d86c4721
[2] https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/commit/GNUmakefile?id=fee8e186e3878c6e9827233efde90bc115801aa3



Signed-off-by: Changqing Li <changqing.li@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>