Refs #163. Obtain the build configure on runtime.

Refs #163. Obtain the build configure on runtime.
openblas_get_config function returns the configure string.
So far, it supports USE64BITINT, NO_CBLAS, NO_LAPACK, NO_LAPACKE,
DYNAMIC_ARCH, NO_AFFINITY.

Example:
 #include <stdio.h>
extern char * openblas_get_config();
void main()
{
  printf("%s\n",openblas_get_config());
  return;
}