[libpng15] Removed some comments that the configure script did not handle

properly from scripts/pnglibconf.dfa and pnglibconf.h.prebuilt.
Bump version to 1.5.22rc02

libpng-manual.txt

@@ -1,6 +1,6 @@
 Libpng-manual.txt - A description on how to use and modify libpng
 
- libpng version 1.5.22rc01 - March 4, 2015
+ libpng version 1.5.22rc02 - March 6, 2015
  Updated and distributed by Glenn Randers-Pehrson
  <glennrp at users.sourceforge.net>
  Copyright (c) 1998-2014 Glenn Randers-Pehrson
@@ -11,7 +11,7 @@ Libpng-manual.txt - A description on how to use and modify libpng
 
  Based on:
 
- libpng versions 0.97, January 1998, through 1.5.22rc01 - March 4, 2015
+ libpng versions 0.97, January 1998, through 1.5.22rc02 - March 6, 2015
  Updated and distributed by Glenn Randers-Pehrson
  Copyright (c) 1998-2014 Glenn Randers-Pehrson
 
@@ -317,7 +317,7 @@ prediction.
 
 If you are intending to keep the file pointer open for use in libpng,
 you must ensure you don't read more than 8 bytes from the beginning
-of the file, and you also have to make a call to png_set_sig_bytes_read()
+of the file, and you also have to make a call to png_set_sig_bytes()
 with the number of bytes you read from the beginning.  Libpng will
 then only check the bytes (if any) that your program didn't read.
 
@@ -4535,13 +4535,13 @@ Other rules can be inferred by inspecting the libpng source.
 
 XIV. Y2K Compliance in libpng
 
-March 4, 2015
+March 6, 2015
 
 Since the PNG Development group is an ad-hoc body, we can't make
 an official declaration.
 
 This is your unofficial assurance that libpng from version 0.71 and
-upward through 1.5.22rc01 are Y2K compliant.  It is my belief that earlier
+upward through 1.5.22rc02 are Y2K compliant.  It is my belief that earlier
 versions were also Y2K compliant.
 
 Libpng only has two year fields.  One is a 2-byte unsigned integer