src/check_symbols: More work around and fixes for symbol detection.

src/check_symbols

@@ -5,9 +5,9 @@
 rm -f libvlc-headers.sym
 
 cat ${srcdir}/../include/vlc_*.h | \
-sed -n -e 's/^\s*VLC_EXPORT\s*([^,]*,\([^,]*\).*).*/\1/p' | \
+sed -n -e 's/^[ ]*VLC_EXPORT[ ]*([^,]*,\([^,]*\),.*/\1/p' | \
 sed -e 's/[^a-zA-Z0-9_]*//' | \
-sort -du > libvlc-headers.sym
+sort -fdu > libvlc-headers.sym
 
 if ! diff -u ${srcdir}/libvlc.sym libvlc-headers.sym; then
 	echo "Mismatching symbols found!"