CDB: Make a local function static

Change-Id: I91f694a6fdfe4f8efb038180da376081ec9d1ad6
Reviewed-by: David Schulz <david.schulz@qt.io>

src/libs/qtcreatorcdbext/stringutils.cpp

@@ -149,7 +149,7 @@ std::string wStringToString(const std::wstring &w)
 }
 
 // Convert an ASCII hex digit to its value 'A'->10
-inline unsigned hexDigit(char c)
+static inline unsigned hexDigit(char c)
 {
     if (c <= '9')
         return c - '0';