Remove export_small_typeof

I think this might have been part of a scheme to avoid an extra
indirection when this symbol is exposed to the linker. We have a similar
technique used for JIT'd modules, but I'm not sure how it's supposed
to work here between libjulia and libjulia-internal.

On Windows, this is broken for embedding currently, and on Linux this
function was just copying from the `small_typeof` in libjulia to a seem-
ingly unused copy of the symbol in libjulia-internal.

For now, this removes the special machinery and replaces it with a single
copy of the data. If we'd like to optimize this in the future, we might
want to use the existing "ijl_" vs. "jl_" pattern

src/jltypes.c

@@ -20,7 +20,6 @@ extern "C" {
 #endif
 
 _Atomic(jl_value_t*) cmpswap_names JL_GLOBALLY_ROOTED;
-jl_datatype_t *small_typeof[(jl_max_tags << 4) / sizeof(*small_typeof)]; // 16-bit aligned, like the GC
 
 // compute empirical max-probe for a given size
 #define max_probe(size) ((size) <= 1024 ? 16 : (size) >> 6)
@@ -2528,17 +2527,6 @@ static jl_tvar_t *tvar(const char *name)
                           (jl_value_t*)jl_any_type);
 }
 
-void export_small_typeof(void)
-{
-    void *copy;
-#ifdef _OS_WINDOWS_
-    jl_dlsym(jl_libjulia_handle, "small_typeof", &copy, 1);
-#else
-    jl_dlsym(jl_libjulia_internal_handle, "small_typeof", &copy, 1);
-#endif
-    memcpy(copy, &small_typeof, sizeof(small_typeof));
-}
-
 #define XX(name) \
     small_typeof[(jl_##name##_tag << 4) / sizeof(*small_typeof)] = jl_##name##_type; \
     jl_##name##_type->smalltag = jl_##name##_tag;
@@ -3360,7 +3348,6 @@ void jl_init_types(void) JL_GC_DISABLED
 
     // override the preferred layout for a couple types
     jl_lineinfonode_type->name->mayinlinealloc = 0; // FIXME: assumed to be a pointer by codegen
-    export_small_typeof();
 }
 
 static jl_value_t *core(const char *name)
@@ -3441,7 +3428,6 @@ void post_boot_hooks(void)
             }
         }
     }
-    export_small_typeof();
 }
 
 void post_image_load_hooks(void) {

src/staticdata.c

@@ -2838,7 +2838,6 @@ JL_DLLEXPORT void jl_set_sysimg_so(void *handle)
 #endif
 
 extern void rebuild_image_blob_tree(void);
-extern void export_small_typeof(void);
 
 static void jl_restore_system_image_from_stream_(ios_t *f, jl_image_t *image, jl_array_t *depmods, uint64_t checksum,
                                 /* outputs */    jl_array_t **restored,         jl_array_t **init_order,
@@ -2917,7 +2916,6 @@ static void jl_restore_system_image_from_stream_(ios_t *f, jl_image_t *image, jl
         small_typeof[(jl_##name##_tag << 4) / sizeof(*small_typeof)] = jl_##name##_type;
         JL_SMALL_TYPEOF(XX)
 #undef XX
-        export_small_typeof();
         jl_global_roots_table = (jl_array_t*)jl_read_value(&s);
         // set typeof extra-special values now that we have the type set by tags above
         jl_astaggedvalue(jl_nothing)->header = (uintptr_t)jl_nothing_type | jl_astaggedvalue(jl_nothing)->header;