Use dedicated method instead of copying conditions. NFC.

llvm-svn: 295172
diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
index 2927199..4ba609b 100644
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -2503,7 +2503,7 @@
 
 bool FunctionDecl::hasBody(const FunctionDecl *&Definition) const {
   for (auto I : redecls()) {
-    if (I->Body || I->IsLateTemplateParsed) {
+    if (I->doesThisDeclarationHaveABody()) {
       Definition = I;
       return true;
     }