change feature guard to power8-vector as that's when the instructions was introduced

Author: lei137

crates/core_arch/src/powerpc/vsx.rs

@@ -178,14 +178,14 @@ mod sealed {
     vec_mergeeo! { vector_float, mergee, mergeo }
 
     #[inline]
-    #[target_feature(enable = "vsx")]
+    #[target_feature(enable = "power8-vector")]
     #[cfg_attr(test, assert_instr(xvmindp))]
     unsafe fn vec_xvmindp(a: vector_double, b: vector_double) -> vector_double {
         xvmindp(a, b)
     }
 
     #[inline]
-    #[target_feature(enable = "vsx")]
+    #[target_feature(enable = "power8-vector")]
     #[cfg_attr(test, assert_instr(xvmaxdp))]
     unsafe fn vec_xvmaxdp(a: vector_double, b: vector_double) -> vector_double {
         xvmaxdp(a, b)
@@ -195,7 +195,7 @@ mod sealed {
     impl super::altivec::sealed::VectorMin<vector_double> for vector_double {
         type Result = vector_double;
         #[inline]
-        #[target_feature(enable = "vsx")]
+        #[target_feature(enable = "power8-vector")]
         unsafe fn vec_min(self, b: vector_double) -> Self::Result {
             vec_xvmindp(self, b)
         }
@@ -205,7 +205,7 @@ mod sealed {
     impl super::altivec::sealed::VectorMax<vector_double> for vector_double {
         type Result = vector_double;
         #[inline]
-        #[target_feature(enable = "vsx")]
+        #[target_feature(enable = "power8-vector")]
         unsafe fn vec_max(self, b: vector_double) -> Self::Result {
             vec_xvmaxdp(self, b)
         }