[master] Imported from libpng-1.6.27.tar

ANNOUNCE

@@ -1,4 +1,4 @@
-Libpng 1.6.26 - October 20, 2016
+Libpng 1.6.27 - December 29, 2016
 
 This is a public release of libpng, intended for use in production codes.
 
@@ -7,53 +7,32 @@ Files available for download:
 Source files with LF line endings (for Unix/Linux) and with a
 "configure" script
 
-   libpng-1.6.26.tar.xz (LZMA-compressed, recommended)
-   libpng-1.6.26.tar.gz
+   libpng-1.6.27.tar.xz (LZMA-compressed, recommended)
+   libpng-1.6.27.tar.gz
 
 Source files with CRLF line endings (for Windows), without the
 "configure" script
 
-   lpng1626.7z  (LZMA-compressed, recommended)
-   lpng1626.zip
+   lpng1627.7z  (LZMA-compressed, recommended)
+   lpng1627.zip
 
 Other information:
 
-   libpng-1.6.26-README.txt
-   libpng-1.6.26-LICENSE.txt
-   libpng-1.6.26-*.asc (armored detached GPG signatures)
+   libpng-1.6.27-README.txt
+   libpng-1.6.27-LICENSE.txt
+   libpng-1.6.27-*.asc (armored detached GPG signatures)
 
-Changes since the last public release (1.6.25):
-
-  Fixed handling zero length IDAT in pngfix (bug report by Agostino Sarubbo,
-    bugfix by John Bowler).
-  Do not issue a png_error() on read in png_set_pCAL() because png_handle_pCAL
-    has allocated memory that libpng needs to free.
-  Conditionally compile png_set_benign_errors() in pngread.c and pngtest.c
-  Issue a png_benign_error instead of a png_error on ADLER32 mismatch
-    while decoding compressed data chunks.
-  Changed PNG_ZLIB_VERNUM to ZLIB_VERNUM in pngpriv.h, pngstruct.h, and
-    pngrutil.c.
-  If CRC handling of critical chunks has been set to PNG_CRC_QUIET_USE,
-    ignore the ADLER32 checksum in the IDAT chunk as well as the chunk CRCs.
-  Issue png_benign_error() on ADLER32 checksum mismatch instead of png_error().
-  Add tests/badcrc.png and tests/badadler.png to tests/pngtest.
-  Merged pngtest.c with libpng-1.7.0beta84/pngtest.c
-  Updated the documentation about CRC and ADLER32 handling.
-  Quieted 117 warnings from clang-3.8 in pngtrans.c, pngread.c,
-     pngwrite.c, pngunknown.c, and pngvalid.c.
-  Quieted the 144 remaining -Wconversion compiler warnings by
-    revising the png_isaligned() macro and trivial changes in png.c,
-    pngerror.c, pngget.c, pngmem.c, pngset.c, pngrtran.c, pngrutil.c,
-    pngwtran.c, pngwrite.c, and pngwutil.c.
-  Quieted (bogus?) clang warnings about "absolute value has no effect"
-    when PNG_USE_ABS is defined.
-  Fixed offsets in contrib/intel/intel_sse.patch
-  Changed integer constant 4294967294 to unsigned 4294967294U in pngconf.h
-    to avoid a signed/unsigned compare in the preprocessor.
-  Use zlib-1.2.8.1 inflateValidate() instead of inflateReset2() to
-    optionally avoid ADLER32 evaluation.
-  Cosmetic change, "ptr != 0" to "ptr != NULL" in png.c and pngrutil.c
-  Despammed email addresses (replaced "@" with " at ").
+Changes since the last public release (1.6.26):
+  Control ADLER32 checking with new PNG_IGNORE_ADLER32 option.
+  Removed the use of a macro containing the pre-processor 'defined'
+    operator.  It is unclear whether this is valid; a macro that
+    "generates" 'defined' is not permitted, but the use of the word
+    "generates" within the C90 standard seems to imply more than simple
+    substitution of an expression itself containing a well-formed defined
+    operation.
+  Added ARM support to CMakeLists.txt (Andreas Franek).
+  Fixed a potential null pointer dereference in png_set_text_2() (bug report
+    and patch by Patrick Keshishian).
 
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