mktemp: remove

Both busybox and coreutils provide mktemp, and the only difference between those
(and standalone mktemp) is that coreutils supports --suffix.

Also mktemp.org has disappeared, so it's fair to assume that the standalone
mktemp (last released in 2010) is dead.

(From OE-Core rev: 59a825ca1e08a7e47fcbc807606103d463280e6c)

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

meta/recipes-extended/packagegroups/packagegroup-core-full-cmdline.bb

@@ -86,7 +86,6 @@ RDEPENDS_packagegroup-core-full-cmdline-utils = "\
     mc-fish \
     mc-helpers \
     mc-helpers-perl \
-    mktemp \
     ncurses \
     net-tools \
     popt \

meta/recipes-extended/packagegroups/packagegroup-core-lsb.bb

@@ -158,7 +158,6 @@ RDEPENDS_packagegroup-core-lsb-core = "\
     make \
     man \
     man-pages \
-    mktemp \
     msmtp \
     patch \
     procps \