Utils: Fix long small string

We used only 6 bit to save the short size but for SmallString with a size
over 64 it is not enough. So we have now to use a uint16 instead of a
uint8 if the size if over 64.

Change-Id: I53558e492b6cb40b739b23a8af83d192a2e11bd2
Reviewed-by: Tim Jenssen <tim.jenssen@qt.io>

src/libs/clangbackendipc/clangbackendipc_global.h

@@ -55,7 +55,7 @@ namespace Utils {
 template <uint Size>
 class BasicSmallString;
 using SmallString = BasicSmallString<31>;
-using PathString = BasicSmallString<191>;
+using PathString = BasicSmallString<190>;
 }
 
 namespace ClangBackEnd {