PPC: perf enhancement: Use larger heap page size on PPC.

src/base/build_config.h

Index: src/base/build_config.h
diff --git a/src/base/build_config.h b/src/base/build_config.h
index 661bf80e6e579311841ff27aa76ba31b3b49ebbd..b8ba4eb8d2c5a406c6355113c378dce8280bdaa7 100644
--- a/src/base/build_config.h
+++ b/src/base/build_config.h
@@ -177,6 +177,11 @@
 
 // Number of bits to represent the page size for paged spaces. The value of 20
 // gives 1Mb bytes per page.
+#if V8_HOST_ARCH_PPC && V8_TARGET_ARCH_PPC && V8_OS_LINUX
+// Bump up for Power Linux due to larger (64K) page size.
+const int kPageSizeBits = 22;
+#else
 const int kPageSizeBits = 20;
+#endif
 
 #endif  // V8_BASE_BUILD_CONFIG_H_