travis: Drop ppc64le native build

as it often fails due Travis CI infrastructure problems
("An error occurred while generating the build script.").
We have ppc64le cross-compilation build, thus this arch is covered.

It looks like non-intel archs are pretty unstable in Travis CI
(s390x had to be drooped in t62cf66294).

Suggested-by: Cyril Hrubis <[email protected]>
Signed-off-by: Petr Vorel <[email protected]>

Author: pevik

.travis.yml

@@ -38,12 +38,6 @@ matrix:
           env: DISTRO=debian:stable VARIANT=minimal TREE=out
           compiler: clang
 
-        # native non-intel
-        - os: linux
-          arch: ppc64le
-          compiler: gcc
-          env: DISTRO=debian:testing
-
         # other builds
         - os: linux
           env: DISTRO=fedora:rawhide MAKE_INSTALL=1