procps-ng: remove unnecessary PKG_BUILD_DEPENDS

procps-ng: remove unnecessary PKG_BUILD_DEPENDS

The package Makefile contains an unnecessary PKG_BUILD_DEPENDS
line that builds gettext and libiconv even in cases where the
build has gettext-full and libiconv-full selected.

This behaviour can and does mask errors in other package Makefiles
that are dependent on libiconv-full if it is compiled before
these packages by causing libiconv-stub to be created and put in
the staging tree and potentially linked against by these
dependent packages when they omit to specify an appropriate
PKG_BUILD_DEPENDS line.

procps-ng does not require gettext or libiconv to be built in
order to compile correctly.

Signed-off-by: Ian Cooper <iancooper@hotmail.com>