Keep two empty lines between declarations for cpp files

src/platform-posix.cc

Index: src/platform-posix.cc
===================================================================
--- src/platform-posix.cc	(revision 15486)
+++ src/platform-posix.cc	(working copy)
@@ -326,6 +326,7 @@
   memmove(dest, src, size);
 }
 
+
 // Initialize to library version so we can call this at any time during startup.
 static OS::MemMoveFunction memmove_function = &MemMoveWrapper;
 
@@ -358,6 +359,7 @@
   init_fast_sqrt_function();
 }
 
+
 // ----------------------------------------------------------------------------
 // POSIX string support.
 //