fixes #11225; generic sandwich problems; [backport:1.2] (#17255)

* fixes #11225; generic sandwich problems; [backport:1.2]
* progress
* delegating these symbols must be done via 'bind'

tests/sandwich/generic_library.nim

@@ -0,0 +1,6 @@
+
+proc libraryFunc*[T](x: T) =
+  mixin mixedIn, indirectlyMixedIn
+  echo mixedIn()
+  echo indirectlyMixedIn()
+

tests/sandwich/helper_module.nim

@@ -0,0 +1,3 @@
+
+proc indirectlyMixedIn*: int =
+  200

tests/sandwich/module_using_generic_library.nim

@@ -0,0 +1,12 @@
+
+import
+  generic_library, helper_module
+
+proc mixedIn: int = 100
+
+proc makeUseOfLibrary*[T](x: T) =
+  bind mixedIn, indirectlyMixedIn
+  libraryFunc(x)
+
+when isMainModule:
+  makeUseOfLibrary "test"

tests/sandwich/tmain.nim

@@ -0,0 +1,9 @@
+discard """
+  output: '''100
+200'''
+"""
+
+import
+  module_using_generic_library
+
+makeUseOfLibrary "test"