Fix alignment issues with Jets.

1. Test that reproduces the failure on macos.
2. Move the alignment macros from manual_constructor.h
   to macros.h and rename them to prevent conflicts.
3. The inline array used by FixedArray is now aligned.
4. Jet has been modified to be eigen friendly.

Change-Id: I4563847a767a92156dabab1ab420f0cdddb8ba77

include/ceres/internal/fixed_array.h

@@ -34,6 +34,7 @@
 
 #include <cstddef>
 #include <glog/logging.h>
+#include "ceres/internal/macros.h"
 #include "ceres/internal/manual_constructor.h"
 
 namespace ceres {
@@ -149,7 +150,7 @@ class FixedArray {
 
   // Allocate some space, not an array of elements of type T, so that we can
   // skip calling the T constructors and destructors for space we never use.
-  ManualConstructor<InnerContainer> inline_space_[kInlineElements];
+  ManualConstructor<InnerContainer> inline_space_[kInlineElements] CERES_ALIGN_ATTRIBUTE(16);
 };
 
 // Implementation details follow