Reland PPC portion of "Detect cache line size on Linux for PPC hosts."

src/ppc/cpu-ppc.cc

Index: src/ppc/cpu-ppc.cc
diff --git a/src/ppc/cpu-ppc.cc b/src/ppc/cpu-ppc.cc
index a42fa53960cddf375ad0966b9d0de29dccacf08c..91ea4000e189bfb01d077969bc554bbc50f9a415 100644
--- a/src/ppc/cpu-ppc.cc
+++ b/src/ppc/cpu-ppc.cc
@@ -25,7 +25,7 @@ void CpuFeatures::FlushICache(void* buffer, size_t size) {
     return;
   }
 
-  const int kCacheLineSize = CpuFeatures::cache_line_size();
+  const int kCacheLineSize = CpuFeatures::icache_line_size();
   intptr_t mask = kCacheLineSize - 1;
   byte *start =
       reinterpret_cast<byte *>(reinterpret_cast<intptr_t>(buffer) & ~mask);