This package appears to include a private copy of valgrind.h. In the latest relase of valgrind 3.10.0 a bug was fixed for ppc32 and support was added for aarch64 and ppc64le. Please either update the private copy of valgrind.h (memcheck.h, callgrind.h, etc) or (better) make your package BuildRequires: valgrind-devel and use the system installed headers.
Fix committed to rawhide to use system valgrind header (v8-3.14.5.10-15.fc22). Google almost certainly isn't going to take the patch I made though, because they don't ever use system headers. You might open a bug against v8 and ask them to simply update their bundled header.