[z]ger: increase multithread threshold

The ones given in 3ae30cd was by far to low because I
mixed m and m*n in my measures. Note that the new ones
are closed to the [z]gemv ones which is comforting
that both are right.

interface/ger.c

@@ -175,7 +175,7 @@ void CNAME(enum CBLAS_ORDER order,
 
 #ifdef SMPTEST
   // Threshold chosen so that speed-up is > 1 on a Xeon E5-2630
-  if(1L * m * n > 24L * GEMM_MULTITHREAD_THRESHOLD)
+  if(1L * m * n > 2048L * GEMM_MULTITHREAD_THRESHOLD)
     nthreads = num_cpu_avail(2);
   else
     nthreads = 1;

interface/zger.c

@@ -214,7 +214,7 @@ void CNAME(enum CBLAS_ORDER order,
 
 #ifdef SMPTEST
   // Threshold chosen so that speed-up is > 1 on a Xeon E5-2630
-  if(1L * m * n > 3L * sizeof(FLOAT) * GEMM_MULTITHREAD_THRESHOLD)
+  if(1L * m * n > 36L * sizeof(FLOAT) * sizeof(FLOAT) * GEMM_MULTITHREAD_THRESHOLD)
     nthreads = num_cpu_avail(2);
   else
     nthreads = 1;