Add ifdefs around conditionally used functions

Author: martin-frbg

kernel/x86_64/sgemv_n_4.c

@@ -115,6 +115,8 @@ static void sgemv_kernel_4x4(BLASLONG n, FLOAT **ap, FLOAT *xo, FLOAT *y, FLOAT
 
 #endif
 
+#ifndef HAVE_SGEMV_N_SKYLAKE_KERNEL				
+
 #ifndef HAVE_KERNEL_4x2
 
 static void sgemv_kernel_4x2( BLASLONG n, FLOAT **ap, FLOAT *x, FLOAT *y, FLOAT *alpha) __attribute__ ((noinline));
@@ -246,6 +248,8 @@ static void sgemv_kernel_4x1(BLASLONG n, FLOAT *ap, FLOAT *x, FLOAT *y, FLOAT *a
 
 #endif
 
+#endif
+
 static void add_y(BLASLONG n, FLOAT *src, FLOAT *dest, BLASLONG inc_dest) __attribute__ ((noinline));
 
 static void add_y(BLASLONG n, FLOAT *src, FLOAT *dest, BLASLONG inc_dest)