pkg-autotools: generic configure fix for powerpc64

pkg-autotools: generic configure fix for powerpc64

Many (100+) packages supported by buildroot contain old configure
scripts (or build them from old versions of autotools) that are unable
to determine how to link shared libraries on powerpc64 and
powerpc64le. This causes that test to erroneously fail on toolchains
that are not "bi-endian" (which is the case for toolchains built by
buildroot), which causes configure to build static libraries instead
of dynamic ones. Although these builds succeed, they tend to cause
linker failures in binaries later linked against them.

Because affected configure files can be discovered automatically, this
patch introduces a hook (enabled only when building for powerpc64 and
powerpc64le) that uses a script to scan and fix each package.

Signed-off-by: Sam Bobroff <sam.bobroff@au1.ibm.com>
Reviewed-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>