CPlusPlus: Inline some simple central functions

Depending on context, callgrind sees contributions of >8% to
the total cost of project parsing for these functions. The
functional are actualy executed executed out-of-line, often
for a function body of one "payload" instruction only.

Inlining removes the call/endbr64/ret overhead.

Change-Id: I6886f08e322fcaa4e0f54d424279e0a8c24e4718
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

src/libs/cplusplus/SymbolNameVisitor.cpp

@@ -41,7 +41,7 @@ void SymbolNameVisitor::accept(Symbol *symbol)
         if (Scope *scope = symbol->enclosingScope())
             accept(scope);
 
-        if (! symbol->isTemplate()) {
+        if (! symbol->asTemplate()) {
             if (const Name *name = symbol->name()) {
                 std::swap(_symbol, symbol);
                 accept(name);