Comment # 4 on bug 927268 from Bruno Friedmann

I've to use the same trick for building sfcgal in Application:Geo

```
# bypass bug 927268 for PowerPC if clang is used above in place of gcc
tmpflags="%{optflags}"
%ifarch ppc64 ppc64le
%if 0%{suse_version} <= 1320
tmpflags=${tmpflags/-fstack-protector}
%endif
%endif

%cmake \
  -DCMAKE_USER_MAKE_RULES_OVERRIDE=OFF \
  -DCMAKE_CXX_FLAGS="${tmpflags} -Doverride=" \
  -DCMAKE_CXX_COMPILER="%{_bindir}/clang++" \
  -DCMAKE_C_COMPILER="%{_bindir}/clang" \
...
```