Runtime support for CFI

Control Flow Integrity support in bionic.

General design:
http://clang.llvm.org/docs/ControlFlowIntegrityDesign.html#shared-library-support

This CL implements subsections "CFI Shadow" and "CFI_SlowPath" in the above document.

Bug: 22033465
Test: bionic device tests
Change-Id: I14dfea630de468eb5620e7f55f92b1397ba06217
diff --git a/linker/linker_phdr.cpp b/linker/linker_phdr.cpp
index a453bef..72549cc 100644
--- a/linker/linker_phdr.cpp
+++ b/linker/linker_phdr.cpp
@@ -42,6 +42,7 @@
 #include "linker_utils.h"
 
 #include "private/bionic_prctl.h"
+#include "private/CFIShadow.h" // For kLibraryAlignment
 
 static int GetTargetElfMachine() {
 #if defined(__arm__)