Refs #193. cblas: move #include out of extern "C" block.

Standard headers may contain C++ templates which are not permitted inside an
extern "C" block. This might be the case when we include <complex.h>.

cblas.h

@@ -1,14 +1,14 @@
 #ifndef CBLAS_H
 #define CBLAS_H
 
+#include <stddef.h>
+#include "common.h"
+
 #ifdef __cplusplus
 extern "C" {
 	/* Assume C declarations for C++ */
 #endif  /* __cplusplus */
 
-#include <stddef.h>
-#include "common.h"
-
 /*Set the number of threads on runtime.*/
 void openblas_set_num_threads(int num_threads);
 void goto_set_num_threads(int num_threads);