Support for powerpc64le requires POWER8 or newer processors. Builds for
older processors are not tested. Require at least POWER8 to avoid
unintentional builds.
* sysdeps/powerpc/powerpc64le/configure.ac: Check for POWER8.
* sysdeps/powerpc/powerpc64le/configure: Update.
On powerpc64le, support for float128 will be enabled, which requires some
compiler features to be present. This patch adds a configure test to check
for such features, which are provided for powerpc64le since GCC 6.2.
Tested for powerpc64 and powerpc64le.
* INSTALL: Regenerate.
* manual/install.texi (Recommended Tools for Compilation): Mention
the powerpc64le-specific requirement in the manual.
* sysdeps/powerpc/powerpc64le/configure.ac: New file with checks
for the compiler features required for building float128.
* sysdeps/powerpc/powerpc64le/configure: New, auto-generated file.
