fix problem with unresolved symbols when multiple shaders call certain

[cmstein]

functions on the GPU (ie. osl_printf()).

Description

Tests

Checklist:

• I have read the contribution guidelines.
• I have previously submitted a Contributor License Agreement.
• I have updated the documentation, if applicable.
• I have ensured that the change is tested somewhere in the testsuite (adding new test cases if necessary).
• My code follows the prevailing code style of this project.

[lgritz]

LGTM, will merge after CI results are complete.

[cmstein]

This fixes a problem I was seeingon the GPU: if I had two shaders that contained a printf(), then the second shader group would report osl_printf as being an unresolved function (the first shader group was fine). If I looked at the PTX for the second shader group, osl_printf was tagged as a "weak" function. Removing the "weak" attribute resolves the problem.

I'm not sure why osl_printf and rend_get_userdata should be different from the other functions in rend_lib.cu.

This is easily reproduced in testsuite/testoptix by adding a printf() to checkerboard.osl and microfacet_test.osl.