fixed: backtrace in crashlog when core name is "core"

This was a regression of r34954.
Also, add a comment in xbmc.sh.in explaining the glob pattern to avoid
this issue coming back in the future.

(cherry picked from commit e4d03498642df8fd29b74affc7e49fe95616aa61)

git-svn-id: https://xbmc.svn.sourceforge.net/svnroot/xbmc/branches/Dharma@35064 568bbfeb-2a22-0410-94d2-cc84cf5bfa90

tools/Linux/xbmc.sh.in

@@ -40,7 +40,8 @@ done
 
 single_stacktrace()
 {
-  find "$1" -maxdepth $2 -name 'core.*' | while read core; do
+  # core filename is either "core.$PID" or "core"
+  find "$1" -maxdepth $2 -name 'core*' | while read core; do
       LC_ALL=C gdb --core="$core" --batch 2> /dev/null | grep -q "^Core was generated by \`$LIBDIR/xbmc/xbmc.bin" || continue
       echo "=====>  Core file: "$core" ($(stat -c%y "$core"))" >> $FILE
       echo "        =========================================" >> $FILE