Move make_unique to source/util. (#1836)

This MakeUnique code is used in places other then source/opt so move it
to source/utils.
diff --git a/BUILD.gn b/BUILD.gn
index 0d06394..b186d35 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -332,6 +332,7 @@
     "source/util/hex_float.h",
     "source/util/ilist.h",
     "source/util/ilist_node.h",
+    "source/util/make_unique.h",
     "source/util/parse_number.cpp",
     "source/util/parse_number.h",
     "source/util/small_vector.h",
@@ -508,7 +509,6 @@
     "source/opt/loop_unswitch_pass.h",
     "source/opt/loop_utils.cpp",
     "source/opt/loop_utils.h",
-    "source/opt/make_unique.h",
     "source/opt/mem_pass.cpp",
     "source/opt/mem_pass.h",
     "source/opt/merge_return_pass.cpp",
@@ -695,6 +695,8 @@
 
   deps = [
     ":spvtools",
+    ":spvtools_language_header_unified1",
+    ":spvtools_val",
   ]
 
   if (build_with_chromium) {