[clang] [SystemZ][z/OS] Implement #pragma export (PR #141671)

[Erich Keane via cfe-commits]

================
@@ -1327,6 +1327,62 @@ void Sema::AddImplicitMSFunctionNoBuiltinAttr(FunctionDecl *FD) {
     FD->addAttr(NoBuiltinAttr::CreateImplicit(Context, V.data(), V.size()));
 }
 
+NamedDecl *Sema::lookupExternCFunctionOrVariable(IdentifierInfo *IdentId,
+                                                 SourceLocation NameLoc,
+                                                 Scope *curScope) {
+  LookupResult Result(*this, IdentId, NameLoc, LookupOrdinaryName);
+  LookupName(Result, curScope);
+  if (!getLangOpts().CPlusPlus)
+    return Result.getAsSingle<NamedDecl>();
+  for (LookupResult::iterator I = Result.begin(); I != Result.end(); ++I) {
----------------
erichkeane wrote:

I'd be open to reviewing a patch(and the community is always open to!) doing modernizations like this in their own PR.  So if you have the bandwidth, please do! 

https://github.com/llvm/llvm-project/pull/141671