qt4: add eglibc-gconv-utf-16 to QtCore RRECOMMENDS when using glibc

This fixes the following warnings when running Qt applications:
QIconvCodec::convertFromUnicode: using Latin-1 for conversion, iconv_open failed
QIconvCodec::convertToUnicode: using Latin-1 for conversion, iconv_open failed

Qt's QString class stores strings internally using UTF-16 encoding.
The UTF-16 iconv module is needed to convert between the system's local
8-bit representation and QString's UTF-16 encoding.

For example, the following functions would be affected:
QString::fromLocal8Bit(...)
QString::toLocal8Bit(...)

If the UTF-16 iconv module couldn't be loaded, it would use Latin-1
encoding instead of the system's encoding for conversion.

[YOCTO #349]

Signed-off-by: Jonathan Liu <net147@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
base.bbclass: Ensure finalised data is displayed in build banner

The build banner displayed at the start of builds can be misleading since
the data store has not been finalised. As easy way to illustrate this is
to use something like:

DEFAULTTUNE = "i586"
DEFAULTTUNE_<machineoverride> = "core2"

and the banner will display the i586 tune yet the core2 tune will be
used. We can avoid this if we finalise a copy of the data before
displaying it.

[YOCTO #4225]

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>