SHMEM/BASE: added missing initializers

- there were missing initializers in shmem segment
  which caused incorrect memory access
- added missing initializers

Signed-off-by: Sergey Oblomov <[email protected]>
(cherry picked from commit 2b8595d)

Author: Sergey Oblomov

oshmem/mca/sshmem/base/sshmem_base_wrappers.c

@@ -85,5 +85,10 @@ shmem_ds_reset(map_segment_t *ds_buf)
     ds_buf->super.va_end = 0;
     ds_buf->seg_size = 0;
     ds_buf->type = MAP_SEGMENT_UNKNOWN;
+    ds_buf->mkeys_cache = NULL;
+    ds_buf->mkeys = NULL;
+    ds_buf->alloc_hints = 0;
+    ds_buf->context = NULL;
+    ds_buf->allocator = NULL;
 }