pan/bi: Implement flog2

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4615>
diff --git a/src/panfrost/bifrost/compiler.h b/src/panfrost/bifrost/compiler.h
index ec9a4ad..96be391 100644
--- a/src/panfrost/bifrost/compiler.h
+++ b/src/panfrost/bifrost/compiler.h
@@ -561,6 +561,7 @@
 /* Special functions */
 
 void bi_emit_fexp2(bi_context *ctx, nir_alu_instr *instr);
+void bi_emit_flog2(bi_context *ctx, nir_alu_instr *instr);
 
 /* BIR manipulation */