extensions/Gentoo/web: remove junk from PNG filegentoo-5.0.6.10

Optimize the size of `gentoo_org.png` by removing all non-visual
information and compressing the file better losslessly.

The old file contained significant data in PNG chunks of type ancillary
& private (see libpng reference) types prVW, mkBF, mkTS, mkBS, mkBT.
They were clearly created by Adobe Fireworks CS3.

`pngcrush` implicitly removes those, but does not remove textual information by
default, which was ALSO inserted by Adobe Fireworks. The `sBIT` chunk is not
needed in our use case, leaving `pHYs` as the only non-critical chunk per the
PNG specification. `pHYs` is kept because it provides DPI information needed
for HiDPI displays.

```
pngcrush \
-reduce \
-brute \
-rem tEXt \
-rem iTXt \
-rem sBIT \
gentoo_org.png.old \
gentoo_org.png.new
```

Size:
Before: 47637
After:   1986
Saving: 45651

Reference: http://www.libpng.org/pub/png/spec/1.1/PNG-Encoders.html#E.Use-of-private-chunks
Closes: https://bugs.gentoo.org/736308
Signed-off-by: Robin H. Johnson <robbat2@gentoo.org>

1 files changed, 0 insertions, 0 deletions

diff --git a/extensions/Gentoo/web/gentoo_org.png b/extensions/Gentoo/web/gentoo_org.png
index a790fe908..c4621baf9 100644
--- a/extensions/Gentoo/web/gentoo_org.png
+++ b/extensions/Gentoo/web/gentoo_org.png