CxxUtils: vec.h move recurring macro to features.h to avoid repeating code

CxxUtils vec.h move recurring macro on if ternary is supported for vector types to features.h to avoid repeating it.

Also we have HAVE_TARGET_CLONES for that particular feature of gcc (both clang and gcc have target).

Control/CxxUtils/CxxUtils/bitscan.h

@@ -130,7 +130,7 @@ namespace CxxUtils {
    * @param x Number to check
    * @return Number of bits set in x.
    */
-#if defined(__x86_64__) && HAVE_GCC_INTRINSICS
+#if defined(__x86_64__) && HAVE_TARGET_CLONES
   // We want to use the popcnt instruction for this if it's available.
   // However, we're still compiling for a Model-T x86_64 by default.
   // Use the target attribute and function multiversioning to use
@@ -146,7 +146,7 @@ namespace CxxUtils {
 #endif
   }
 
-#if defined(__x86_64__) && HAVE_GCC_INTRINSICS
+#if defined(__x86_64__) && HAVE_TARGET_CLONES
   __attribute__ ((target_clones ("popcnt,default")))
 #endif
   inline unsigned count_ones(unsigned long x) {
@@ -158,7 +158,7 @@ namespace CxxUtils {
   }
 
 
-#if defined(__x86_64__) && HAVE_GCC_INTRINSICS
+#if defined(__x86_64__) && HAVE_TARGET_CLONES
   __attribute__ ((target_clones ("popcnt,default")))
 #endif
   inline unsigned count_ones(unsigned long long x) {