Add libpng 1.6.6.

libs/lpng166/configure

@@ -0,0 +1,19 @@
+
+echo "
+  There is no \"configure\" script in this distribution (*.zip or *.7z) of
+  libpng-1.6.6.
+
+  Instead, please copy the appropriate makefile for your system from the
+  \"scripts\" directory.  Read the INSTALL file for more details.
+
+  Update, July 2004: you can get a \"configure\" based distribution
+  from the libpng distribution sites.  Download the file
+  libpng-1.6.6.tar.gz, libpng-1.6.6.tar.xz, or libpng-1.6.6.tar.bz2
+
+  If the line endings in the files look funny, which is likely to be the
+  case if you were trying to run \"configure\" on a Linux machine, you may
+  wish to get the other distribution of libpng.  It is available in both
+  tar.gz/tar.xz (UNIX style line endings, with \"configure\") and .7z/.zip
+  (DOS style line endings, without \"configure\") formats.
+"
+