[totem-pl-parser] Fix mmap error checking

[Philip Withnall <pwithnall src gnome org>]

commit 7e4f4a64336a41da86c322894d4c5d2ea697a089
Author: Michael McConville <mmcco mykolab com>
Date:   Sat Jan 30 17:41:35 2016 -0500

    Fix mmap error checking
    
    mmap returns MAP_FAILED, not NULL, on failure.

 plparse/xmlparser.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/plparse/xmlparser.c b/plparse/xmlparser.c
index ee55c39..2a84b64 100644
--- a/plparse/xmlparser.c
+++ b/plparse/xmlparser.c
@@ -924,7 +924,7 @@ int main (int argc, char **argv)
       continue;
     }
     buf = mmap (NULL, st.st_size, PROT_READ, MAP_SHARED, fd, 0);
-    if (!buf)
+    if (buf == MAP_FAILED)
     {
       perror (argv[i]);
       if (close (fd))