gallium/tests: make trivial test libpipe_loader static
When building mesa with build-tests flag, the gallium trivial tests are build but it does not work because targets/pipe-loader is not built.
This issue can be fixed by either building targets/pipe-loader for enabled drivers such as radeonsi or link libpipe_loader_static library for trivial tests.
This patch fixes the trivial tests failing to load gallium radeonsi driver issue by linking libpipe_loader_static library for trivial tests.
Edited by Yogesh Mohan Marmithu