Separate art::Exec from utils

The rest of utils.cc does not depend on art::Runtime. This separates
the part dependent on that class, so that including utils.cc in the
build does not require the entire Runtime. Another preparatory cleanup
to getting tools to build on Windows.

Bug: 22322814
Test: test-art
Change-Id: I194ff363fc2ab87e5311ecea6973a2d0fad2621d
diff --git a/dexlayout/dexlayout_test.cc b/dexlayout/dexlayout_test.cc
index 46a1c43..da1e1d2 100644
--- a/dexlayout/dexlayout_test.cc
+++ b/dexlayout/dexlayout_test.cc
@@ -23,6 +23,7 @@
 
 #include "base/unix_file/fd_file.h"
 #include "common_runtime_test.h"
+#include "exec_utils.h"
 #include "utils.h"
 
 namespace art {