Revert "[clang] ASTImporter: Fix importing of va_list types and declarations"

This reverts commit 5f820c0f55cd9d4f4520cc92eae0a1c4afe05a54.

Apparently it breaks aarch64 buildbots.
https://lab.llvm.org/buildbot#builders/188/builds/21591
diff --git a/clang-tools-extra/clang-tidy/altera/StructPackAlignCheck.cpp b/clang-tools-extra/clang-tidy/altera/StructPackAlignCheck.cpp
index 1735242..b5f8d08 100644
--- a/clang-tools-extra/clang-tidy/altera/StructPackAlignCheck.cpp
+++ b/clang-tools-extra/clang-tidy/altera/StructPackAlignCheck.cpp
@@ -19,11 +19,10 @@
 namespace altera {
 
 void StructPackAlignCheck::registerMatchers(MatchFinder *Finder) {
-  Finder->addMatcher(
-      recordDecl(isStruct(), isDefinition(),
-                 unless(anyOf(isExpansionInSystemHeader(), isImplicit())))
-          .bind("struct"),
-      this);
+  Finder->addMatcher(recordDecl(isStruct(), isDefinition(),
+                                unless(isExpansionInSystemHeader()))
+                         .bind("struct"),
+                     this);
 }
 
 CharUnits