Export jl_declare_constant_val (#59192)

Closes #59184

(cherry picked from commit 13f6b3b)

Author: Taaitaaiger

src/jl_exported_funcs.inc

@@ -183,6 +183,7 @@
     XX(jl_gdblookup) \
     XX(jl_generating_output) \
     XX(jl_declare_const_gf) \
+    XX(jl_declare_constant_val) \
     XX(jl_gensym) \
     XX(jl_getaffinity) \
     XX(jl_getallocationgranularity) \