Utils: Activate copy constructor and assignment

The move only patter is quite powerful but has the drawback that some
STL algorithms get quite complicated. For short string or const references
should be not difference to a move. So we activate them for all cases.

Change-Id: I959c13796e69c45f31bb0ecbbe64a70d39961e3f
Reviewed-by: Tim Jenssen <tim.jenssen@qt.io>

src/libs/utils/smallstring.h

@@ -155,10 +155,6 @@ public:
             Memory::deallocate(m_data.allocated.data.pointer);
     }
 
-#if !defined(UNIT_TESTS) && !(defined(_MSC_VER) && _MSC_VER < 1900)
-    BasicSmallString(const BasicSmallString &other) = delete;
-    BasicSmallString &operator=(const BasicSmallString &other) = delete;
-#else
     BasicSmallString(const BasicSmallString &string)
     {
         if (string.isShortString() || string.isReadOnlyReference())
@@ -175,7 +171,6 @@ public:
 
         return *this;
     }
-#endif
 
     BasicSmallString(BasicSmallString &&other) noexcept
     {