ClangBackEnd: Fix mis-detection of operator<

Inside the body of a function template, clang reports a different cursor
type for operators in some cases. Make sure we don't mistake such
operator< or operator> as opening or closing a template, respectively.

Fixes: QTCREATORBUG-25596
Change-Id: Ifc357e199ea13e44ac501613639e667c333d48e3
Reviewed-by: David Schulz <david.schulz@qt.io>

tests/unit/unittest/data/highlightingmarks.cpp

@@ -771,3 +771,20 @@ void func(T v) {
 }
 
 static std::vector<std::pair<int, int>> pv;
+
+template <class T, long S>
+struct vecn
+{
+    T v[S];
+};
+
+template <class T, long S>
+static inline constexpr vecn<T, S> operator<(vecn<T, S> a, vecn<T, S> b)
+{
+    vecn<T, S> x = vecn<T, S>{};
+    for(long i = 0; i < S; ++i)
+    {
+        x[i] = a[i] < b[i];
+    }
+    return x;
+}