Fix to build with nvcc in path (crux)

configure.ac

@@ -147,17 +147,20 @@ AC_ARG_WITH([nvml],
 
 AM_CONDITIONAL([HAVE_NVML], [test -n "$with_nvml"])
 
+NVCC="nvcc"
+
 if test -n "$with_cuda"
 then
   CUDA_INCLUDES="-I$with_cuda/include"
   CUDA_LIBS="-lcudart"
   CUDA_LDFLAGS="-L$with_cuda/lib$SUFFIX"
+  if test -x "$with_cuda/bin/nvcc"
     NVCC="$with_cuda/bin/nvcc"
+  fi
 else
   CUDA_INCLUDES="-I/usr/local/cuda/include"
   CUDA_LIBS="-lcudart -static-libstdc++"
   CUDA_LDFLAGS="-L/usr/local/cuda/lib$SUFFIX"
-  NVCC="nvcc"
 fi
 
 if test -n "$with_nvml" ; then