groff: remove redundant code snippet

The exact same code snippet exists both in do_install_append and
do_install_append_class-native which is not necessary.

Remove it from do_install_append_class-native.

Signed-off-by: Ming Liu <ming.liu@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
gawk: fix optional dependency mpfr

 Gawk was failing to compile because of the optional feature mpfr if it found
 libmpfr on build host and linked against that or mpfr existed in sysroot but
 not in deploy, or if gawk was pulled from sstate and someone had mpfr built.

 [YOCTO# 6473]

Signed-off-by: Roxana Ciobanu <roxana.ciobanu@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
groff: Fix build on Fedora 17 for 1.18.1.4

The commit 79fc5576:
[ groff: Fix build on Fedora 17 ]

was applied to 1.22.2, but it's also needed by 1.18.1.4 to solve a same
issue.

Signed-off-by: Ming Liu <ming.liu@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>