if not already defined.

because usleep() is deprecated.

complete without setjmp support (bug report by Claudio Fontana)

/readpng2.c from the previous update.

compiler complaints about unused pointers.

contrib/pngminus/*.c

0644 to 0755 (Cosmin).

because they were handled improperly by Portland Group's PGI-14.1 - PGI-14.3
when using its "__builtin_pow()" function.

contrib/examples/*.c

instead of the default.

implementation of the ARM NEON discovery function to be set at
build-time and provide sample implementations from the current code in the
contrib/arm-neon subdirectory. The __linux__ code has also been changed to
compile and link on Android by using /proc/cpuinfo, and the old linux code
is in contrib/arm-neon/linux-auxv.c.  The new code avoids POSIX and Linux
dependencies apart from opening /proc/cpuinfo and is C90 compliant.

PNG_MAXIMUM_INFLATE_WINDOW option, so #define it out when appropriate in
pngvalid.c

with test programs.