XFA: Rename libpng to libpng16.

third_party/libpng16/0000-build-config.patch

-diff a/third_party/libpng/pngmem.c b/third_party/libpng/pngmem.c
---- a/third_party/libpng/pngmem.c
-+++ b/third_party/libpng/pngmem.c
+diff a/third_party/libpng16/pngmem.c b/third_party/libpng16/pngmem.c
+--- a/third_party/libpng16/pngmem.c
++++ b/third_party/libpng16/pngmem.c
 @@ -19,6 +19,9 @@
  
  #include "pngpriv.h"
  
 +void*  FXMEM_DefaultAlloc(int byte_size, int);
 +void   FXMEM_DefaultFree(void* pointer, int);
 +
  #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
  /* Free a png_struct */
  void /* PRIVATE */
 @@ -92,7 +95,7 @@
  
        else
  #endif
 -         return malloc((size_t)size); /* checked for truncation above */
 +         return FXMEM_DefaultAlloc((int)size, 0);
     }
  
     else
 @@ -249,7 +252,7 @@
        return;
  #endif /* USER_MEM */
  
 -   free(ptr);
 +   FXMEM_DefaultFree(ptr, 0);
  }
  
  #ifdef PNG_USER_MEM_SUPPORTED
-diff a/third_party/libpng/pngstruct.h b/third_party/libpng/pngstruct.h
---- a/third_party/libpng/pngstruct.h
-+++ b/third_party/libpng/pngstruct.h
+diff a/third_party/libpng16/pngstruct.h b/third_party/libpng16/pngstruct.h
+--- a/third_party/libpng16/pngstruct.h
++++ b/third_party/libpng16/pngstruct.h
 @@ -27,7 +27,7 @@
     /* We must ensure that zlib uses 'const' in declarations. */
  #  define ZLIB_CONST
  #endif
 -#include "zlib.h"
 +#include "third_party/zlib_v128/zlib.h"
  #ifdef const
     /* zlib.h sometimes #defines const to nothing, undo this. */
  #  undef const