lapack_calls.cpp must only be compiled if USE_LAPACK is defined

src/libnptm/lapack_calls.cpp

@@ -12,8 +12,8 @@
 #endif
 #endif
 
-void zinvert(std::complex<double> **mat, lapack_int n, int &jer) {
 #ifdef USE_LAPACK
+void zinvert(std::complex<double> **mat, lapack_int n, int &jer) {
   jer = 0;
   __complex__ double *arr = new __complex__ double[n * n];
   const __complex__ double uim = 1.0*I;
@@ -44,5 +44,5 @@ void zinvert(std::complex<double> **mat, lapack_int n, int &jer) {
   }
   delete[] IPIV;
   delete[] arr;
-#endif
 }
+#endif