Fix use of custom pragmas in generic procs (#8165)

Fixes #7626

tests/pragmas/tcustom_pragma.nim

@@ -137,4 +137,12 @@ block:
   static:
     assert hasIntSerKey
     assert strSerKey == "string"
-    assert nestedItemDefVal == "Nimmers of the world, unite!"
+    assert nestedItemDefVal == "Nimmers of the world, unite!"
+
+block:
+  template simpleAttr {.pragma.}
+
+  type Annotated {.simpleAttr.} = object
+
+  proc generic_proc[T]() =
+    assert Annotated.hasCustomPragma(simpleAttr)