Update version to 5.6

TBR=machenbach@chromium.org
NOTREECHECKS=true
NOTRY=true

Review-Url: https://codereview.chromium.org/2397153002
Cr-Commit-Position: refs/heads/master@{#40037}

include/v8-version.h

@@ -9,7 +9,7 @@
 // NOTE these macros are used by some of the tool scripts and the build
 // system so their names cannot be changed without changing the scripts.
 #define V8_MAJOR_VERSION 5
-#define V8_MINOR_VERSION 5
+#define V8_MINOR_VERSION 6
 #define V8_BUILD_NUMBER 0
 #define V8_PATCH_LEVEL 0