[Bug]: OpenRV loads libpng 1.5 before 1.6, which breaks io_png plugin

[geffrak]

What happened?

In the commercial RV distribution (2022.3.1), rv.bin links directly against libpng16.so. However, the rv.bin that is produced by the OpenRV build does not directly link against libpng at all. The end result of this is that when OpenRV runs, it ends up loading libpng15.so (as a side-effect of loading its dependencies) before libpng16.so. Since multiple versions of libpng cannot coexist within the same symbol namespace, this load order breaks the functionality of the io_png plugin, since it apparently relies on some specific features/functionality of the newer png library version.

The end result is that OpenRV cannot read PNG files, instead producing these warning error messages when trying to load them: ​

libpng warning: Application built with libpng-1.6.20 but running with 1.5.13
ERROR: plugin 'IOpng' cannot read '/path/to/image.png': PNG: error creating read struct /path/to/image.png
INFO: trying brute force to find an image reader for image.png

​ Using LD_PRELOAD to force-load libpng16.so in OpenRV fixes this error, which confirms that the library load order is important to allowing RV to function correctly.

It seems like the solution would be to ensure that rv.bin links directly against libpng16.so, but we have not tested this yet, as we're getting by with LD_PRELOAD.

CentOS 7.8.2003 OpenRV runtime version info: Version 2023.0.0, built on Feb 1 2023 at 11:45:25 (HEAD=9c6adc2).

List all the operating systems versions where this is happening

CentOS 7.8.2003

On what computer hardware is this happening?

N/A

Relevant console log output

libpng warning: Application built with libpng-1.6.20 but running with 1.5.13
ERROR: plugin 'IOpng' cannot read '/path/to/image.png': PNG: error creating read struct /path/to/image.png
INFO: trying brute force to find an image reader for image.png

Environment variables

N/A

Extra information

Reported here: https://github.com/AcademySoftwareFoundation/OpenRV/discussions/88

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