third_party/stm32cube: stm32cube_headers vis

Added pw_third_party_stm32cube_CORE_INIT to visibility
list.

Change-Id: I4f98175d2f7303171a9870afa260568a0030c19f
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/84748
Reviewed-by: Armando Montanez <amontanez@google.com>
Commit-Queue: Armando Montanez <amontanez@google.com>
diff --git a/third_party/stm32cube/BUILD.gn b/third_party/stm32cube/BUILD.gn
index 8cfc16b..576c958 100644
--- a/third_party/stm32cube/BUILD.gn
+++ b/third_party/stm32cube/BUILD.gn
@@ -121,7 +121,10 @@
     "STM32CUBE_HEADER=\"${files.family}.h\"",
     "__ARMCC_VERSION=0",  # workaround for bug at stm32l552xx.h:1303
   ]
-  visibility = [ ":*" ]
+  visibility = [
+    ":*",
+    pw_third_party_stm32cube_CORE_INIT,
+  ]
 }
 
 config("public_include_paths") {