coord;sse: add configuration option to enable SSE specialisation

CMakeLists.txt

@@ -224,10 +224,6 @@ list (
     coord/init.hpp
     coord/iostream.hpp
     coord/ops.hpp
-    coord/simd.cpp
-    coord/simd.hpp
-    coord/simd_sse.hpp
-    coord/simd_neon.hpp
     coord/store.hpp
     coord/traits.hpp
     cpp.cpp
@@ -428,6 +424,16 @@ list (
     view.hpp
 )
 
+option (SIMD "enable simd support" OFF)
+
+if (SIM)
+    list (APPEND UTIL_FILES
+        "coord/simd.cpp"
+        "coord/simd.hpp"
+        "coord/simd_sse.hpp"
+        "coord/simd_neon.hpp"
+    )
+endif ()
 
 ##-----------------------------------------------------------------------------
 ## We shouldn't be building into the source directory, but I can't stand trying
@@ -505,7 +511,6 @@ if (TESTS)
         colour
         comparator
         coord
-        coord/simd
         encode/base
         endian
         exe
@@ -575,6 +580,12 @@ if (TESTS)
         view
     )
 
+        if (SIMD)
+            list (APPEND TEST_BIN
+                coord/simd
+            )
+        endif()
+
     foreach(t ${TEST_BIN})
         string(REPLACE "/" "_" name "test/${t}")
         add_executable(util_${name} test/${t}.cpp)