mark xbuffer as volatile to work around gcc15.1 optimizer bug

Author: martin-frbg

kernel/power/dgemv_n.c

@@ -147,7 +147,7 @@ int CNAME(BLASLONG m, BLASLONG n, BLASLONG dummy1, FLOAT alpha, FLOAT *a, BLASLO
 	BLASLONG m3;
 	BLASLONG n2;
 	BLASLONG lda4 =  lda << 2;
-	FLOAT xbuffer[8] __attribute__ ((aligned (16)));
+	volatile FLOAT xbuffer[8] __attribute__ ((aligned (16)));
 	FLOAT *ybuffer;
 
         if ( m < 1 ) return(0);