Sema: fix typo in diag about accepted access-levels on imports

Author: xymus

include/swift/AST/DiagnosticsSema.def

@@ -2455,7 +2455,7 @@ ERROR(spi_only_imports_not_enabled, none,
 ERROR(access_level_on_import_unsupported, none,
       "The access level %0 is unsupported on imports: "
       "only 'public', 'package', 'internal', 'fileprivate' and 'private' "
-      "are unsupported",
+      "are accepted",
       (DeclAttribute))
 ERROR(access_level_conflict_with_exported,none,
       "'%0' is incompatible with %1; it can only be applied to public imports",

test/Sema/access-level-import-parsing.swift

@@ -26,4 +26,4 @@ package import PackageLib // expected-warning {{package import of 'PackageLib' w
 internal import InternalLib
 fileprivate import FileprivateLib
 private import PrivateLib
-open import OpenLib // expected-error {{The access level 'open' is unsupported on imports: only 'public', 'package', 'internal', 'fileprivate' and 'private' are unsupported}}
+open import OpenLib // expected-error {{The access level 'open' is unsupported on imports: only 'public', 'package', 'internal', 'fileprivate' and 'private' are accepted}}