Kill constants.h and fix some copyright headers.

Change-Id: I51c04d731d6de035328781d8ac134ad6fcf49897
diff --git a/src/compiler_llvm/compilation_unit.cc b/src/compiler_llvm/compilation_unit.cc
index ae87395..c5952f0 100644
--- a/src/compiler_llvm/compilation_unit.cc
+++ b/src/compiler_llvm/compilation_unit.cc
@@ -16,7 +16,7 @@
 
 #include "compilation_unit.h"
 
-#include "constants.h"
+#include "instruction_set.h"
 #include "ir_builder.h"
 #include "logging.h"