Adapt to clang::MaterializeTemporaryExpr::GetTemparyExpr rename

...in <https://github.com/llvm/llvm-project/commit/
b0561b3346e7bf0ae974995ca95b917eebde18e1> "[NFC] Refactor representation of
materialized temporaries"

Change-Id: I02fbf6765f9713e4d457f07521129cc9d8db5751
Reviewed-on: https://gerrit.libreoffice.org/83669
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

compilerplugins/clang/plugin.cxx

@@ -18,6 +18,7 @@
 #include <clang/Basic/FileManager.h>
 #include <clang/Lex/Lexer.h>
 
+#include "compat.hxx"
 #include "pluginhandler.hxx"
 
 /*
@@ -30,7 +31,7 @@ namespace {
 
 Expr const * skipImplicit(Expr const * expr) {
     if (auto const e = dyn_cast<MaterializeTemporaryExpr>(expr)) {
-        expr = e->GetTemporaryExpr()->IgnoreImpCasts();
+        expr = compat::getSubExpr(e)->IgnoreImpCasts();
     }
     if (auto const e = dyn_cast<CXXBindTemporaryExpr>(expr)) {
         expr = e->getSubExpr();