[PUSHED] OpenMP: Add omp_get_device_distances routine: Gracefully handle failure to open Linux sysfs file for NUMA node [PR125877]

[Thomas Schwinge]

Fix-up for commit 8af1592882509fbead16e30fd2d056330a9609e4
"OpenMP: Add omp_get_device_distances routine [PR125877]".  Without this,
'libgomp/config/linux/numa.c:gomp_get_numa_distance' faults when trying to
'fscanf' from the null pointer upon 'fopen' failure.

        PR libgomp/125877
        libgomp/
        * config/linux/numa.c (gomp_get_numa_distance): Gracefully handle
        failure to open Linux sysfs file for NUMA node.
---
 libgomp/config/linux/numa.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/libgomp/config/linux/numa.c b/libgomp/config/linux/numa.c
index d43b34b98dd..a3d84870e6e 100644
--- a/libgomp/config/linux/numa.c
+++ b/libgomp/config/linux/numa.c
@@ -85,6 +85,11 @@ gomp_get_numa_distance (int node1, int node2)
            return -1;
          int distance = -1;
          FILE *in = fopen (filename, "r");
+         if (!in)
+           {
+             free (numa_distances);
+             return -1;
+           }
          for (int j = 0; j < cnt; j++)
            {
              fscanf (in, "%d", &distance);
-- 
2.53.0