toolchain: misc fixes (branch yem/toolchain-fixes)

Hello All!

This series introduces two fixes in the external toolchain handling:

- reject "distro-class" toolchains, i.e. the cross-oolchains packaged in Debian and its derivatives, since those toolchains are both non-relocatable and tainted with a lot of crap (i.e. non-libc libraries) which make them unfit for use by Buildroot;

- try harder to find the gconv modules for those multi-arch toolchains, since there may be gconv modules for each variant, and thus would be located out-side the main sysroot.

Changes v2 -> v3:
- update comment for distro-class toolchains (Thomas, Arnout)
- use TOOLCHAIN_EXTERNAL_PREFIX instead of asking gcc (Thomas)

Regards,
Yann E. MORIN.

The following changes since commit 9b8481671e9d0c6abc90d669f99c6925eda86c96:

package/dovecot: bump version to 2.2.16 (2015-03-17 13:03:02 +0100)

are available in the git repository at:

git://git.busybox.net/~ymorin/git/buildroot yem/toolchain-fixes

for you to fetch changes up to 1d2730901d20f1f9bfcfde77883a385b49c73b00:

toolchain: fix installing gconv libs with multi-arch toolchain (2015-03-17 15:04:23 +0100)

----------------------------------------------------------------
Yann E. MORIN (2):
toolchain/external: do not accept distro-class toolchains
toolchain: fix installing gconv libs with multi-arch toolchain

 toolchain/helpers.mk   |  8 ++++++++
 toolchain/toolchain.mk | 26 ++++++++++++++++++--------
 2 files changed, 26 insertions(+), 8 deletions(-)

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