Remove the "last changed" version information from source comments

Makefile.am

 # Makefile.am, the source file for Makefile.in (and hence Makefile), is
 #
+# Copyright (c) 2018 Cosmin Truta
 # Copyright (c) 2004-2016 Glenn Randers-Pehrson
-# Last changed in libpng 1.6.25 [September 1, 2016]
 #
 # This code is released under the libpng license.
 # For conditions of distribution and use, see the disclaimer

arm/arm_init.c

 
 /* arm_init.c - NEON optimised filter functions
  *
+ * Copyright (c) 2018 Cosmin Truta
  * Copyright (c) 2014,2016 Glenn Randers-Pehrson
  * Written by Mans Rullgard, 2011.
- * Last changed in libpng 1.6.22 [May 26, 2016]
  *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
  * and license in png.h
  */
+
 /* Below, after checking __linux__, various non-C90 POSIX 1003.1 functions are
  * called.
  */

arm/filter_neon.S

 
 /* filter_neon.S - NEON optimised filter functions
  *
+ * Copyright (c) 2018 Cosmin Truta
  * Copyright (c) 2014,2017 Glenn Randers-Pehrson
  * Written by Mans Rullgard, 2011.
- * Last changed in libpng 1.6.31 [July 27, 2017]
  *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer

arm/filter_neon_intrinsics.c

 
 /* filter_neon_intrinsics.c - NEON optimised filter functions
  *
+ * Copyright (c) 2018 Cosmin Truta
  * Copyright (c) 2014,2016 Glenn Randers-Pehrson
  * Written by James Yu <james.yu at linaro.org>, October 2013.
  * Based on filter_neon.S, written by Mans Rullgard, 2011.
  *
- * Last changed in libpng 1.6.22 [May 26, 2016]
- *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
  * and license in png.h

intel/filter_sse2_intrinsics.c

 
 /* filter_sse2_intrinsics.c - SSE2 optimized filter functions
  *
+ * Copyright (c) 2018 Cosmin Truta
  * Copyright (c) 2016-2017 Glenn Randers-Pehrson
  * Written by Mike Klein and Matt Sarett
  * Derived from arm/filter_neon_intrinsics.c
  *
- * Last changed in libpng 1.6.31 [July 27, 2017]
- *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
  * and license in png.h

intel/intel_init.c

 
 /* intel_init.c - SSE2 optimized filter functions
  *
+ * Copyright (c) 2018 Cosmin Truta
  * Copyright (c) 2016-2017 Glenn Randers-Pehrson
  * Written by Mike Klein and Matt Sarett, Google, Inc.
  * Derived from arm/arm_init.c
  *
- * Last changed in libpng 1.6.29 [March 16, 2017]
- *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
  * and license in png.h

mips/filter_msa_intrinsics.c

 
 /* filter_msa_intrinsics.c - MSA optimised filter functions
  *
+ * Copyright (c) 2018 Cosmin Truta
  * Copyright (c) 2016 Glenn Randers-Pehrson
  * Written by Mandar Sahastrabuddhe, August 2016.
- * Last changed in libpng 1.6.25 [September 1, 2016]
  *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
  * and license in png.h
  */
+
 #include <stdio.h>
 #include <stdint.h>
 #include "../pngpriv.h"

mips/mips_init.c

 
 /* mips_init.c - MSA optimised filter functions
  *
+ * Copyright (c) 2018 Cosmin Truta
  * Copyright (c) 2016 Glenn Randers-Pehrson
  * Written by Mandar Sahastrabuddhe, 2016.
- * Last changed in libpng 1.6.25 [September 1, 2016]
  *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
  * and license in png.h
  */
+
 /* Below, after checking __linux__, various non-C90 POSIX 1003.1 functions are
  * called.
  */

powerpc/filter_vsx_intrinsics.c

 /* filter_vsx_intrinsics.c - PowerPC optimised filter functions
  *
+ * Copyright (c) 2018 Cosmin Truta
  * Copyright (c) 2017 Glenn Randers-Pehrson
  * Written by Vadim Barkov, 2017.
- * Last changed in libpng 1.6.29 [March 16, 2017]
  *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
  * and license in png.h
  */
+
 #include <stdio.h>
 #include <stdint.h>
 #include "../pngpriv.h"

powerpc/powerpc_init.c

 
 /* powerpc_init.c - POWERPC optimised filter functions
  *
+ * Copyright (c) 2018 Cosmin Truta
  * Copyright (c) 2017 Glenn Randers-Pehrson
  * Written by Vadim Barkov, 2017.
- * Last changed in libpng 1.6.29 [March 16, 2017]
  *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
  * and license in png.h
  */
+
 /* Below, after checking __linux__, various non-C90 POSIX 1003.1 functions are
  * called.
  */