[libpng17] Bump version to 1.7.0beta58

ANNOUNCE

@@ -1,5 +1,5 @@
 
-Libpng 1.7.0beta57 - March 17, 2015
+Libpng 1.7.0beta58 - March 17, 2015
 
 This is not intended to be a public release.  It will be replaced
 within a few weeks by a public version or by another test version.
@@ -9,20 +9,20 @@ Files available for download:
 Source files with LF line endings (for Unix/Linux) and with a
 "configure" script
 
-   1.7.0beta57.tar.xz (LZMA-compressed, recommended)
-   1.7.0beta57.tar.gz
+   1.7.0beta58.tar.xz (LZMA-compressed, recommended)
+   1.7.0beta58.tar.gz
 
 Source files with CRLF line endings (for Windows), without the
 "configure" script
 
-   lp170b57.7z  (LZMA-compressed, recommended)
-   lp170b57.zip
+   lp170b58.7z  (LZMA-compressed, recommended)
+   lp170b58.zip
 
 Other information:
 
-   1.7.0beta57-README.txt
-   1.7.0beta57-LICENSE.txt
-   libpng-1.7.0beta57-*.asc (armored detached GPG signatures)
+   1.7.0beta58-README.txt
+   1.7.0beta58-LICENSE.txt
+   libpng-1.7.0beta58-*.asc (armored detached GPG signatures)
 
 Changes since the last public release (1.6.0):
 
@@ -750,13 +750,15 @@ Version 1.7.0beta56 [March 11, 2015]
   Updated CMakeLists.txt to add OSX framework, change YES/NO to ON/OFF
     for consistency, and remove some useless tests (Alexey Petruchik).
 
-Version 1.7.0beta57 [March 17, 2015]
+Version 1.7.0beta57 [March 16, 2015]
   Remove pnglibconf.h, pnglibconf.c, and pnglibconf.out instead of
     pnglibconf.* in "make clean" (Cosmin).
   Fix bug in calculation of maxbits, in png_write_sBIT, introduced
     in libpng-1.6.17beta01 (John Bowler).
   Revert change to png_default_read_data() made in libpng-1.7.0beta55.
 
+Version 1.7.0beta58 [March 17, 2015]
+
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