Utils: Add more constexpr to SmallString

Change-Id: I480ef040a8d9c5b9edc515c7fd58db2fad42dc86
Reviewed-by: Tim Jenssen <tim.jenssen@qt.io>

src/libs/utils/smallstringiterator.h

@@ -39,6 +39,7 @@ template <class Category,
           typename Reference = Type&>
 struct SmallStringIterator : public  std::iterator<Category, Type, DistanceType, Pointer, Reference>
 {
+    constexpr
     SmallStringIterator() noexcept = default;
 
     constexpr

src/libs/utils/smallstringliteral.h

@@ -66,11 +66,13 @@ public:
         return Q_LIKELY(isShortString()) ? m_data.shortString.shortStringSize : m_data.allocated.data.size;
     }
 
+    constexpr
     const_iterator begin() const noexcept
     {
         return data();
     }
 
+    constexpr
     const_iterator end() const noexcept
     {
         return data() + size();
@@ -102,6 +104,7 @@ public:
         return m_data.shortString.isReadOnlyReference;
     }
 
+    constexpr
     operator SmallStringView() const
     {
         return SmallStringView(data(), size());

src/libs/utils/smallstringview.h

@@ -97,11 +97,13 @@ public:
         return m_size == 0;
     }
 
+    constexpr
     const_iterator begin() const noexcept
     {
         return data();
     }
 
+    constexpr
     const_iterator end() const noexcept
     {
         return data() + size();
@@ -140,8 +142,6 @@ public:
         return m_pointer[0] == characterToSearch;
     }
 
-
-
 private:
     const char *m_pointer;
     size_type m_size;