coverity#1438473 silence Logically dead code

Change-Id: I10b3821311515bb5148dab698f07d902c5c73100
Reviewed-on: https://gerrit.libreoffice.org/59822
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

include/rtl/stringutils.hxx

@@ -184,6 +184,29 @@ struct ConstCharArrayDetector< const char[ N ], T >
 #endif
     static char const * toPointer(char const (& literal)[N]) { return literal; }
 };
+
+#if defined(__COVERITY__)
+//to silence over zealous warnings that the loop is logically dead
+//for the single char case
+template< typename T >
+struct ConstCharArrayDetector< const char[ 1 ], T >
+{
+    typedef T Type;
+    static const std::size_t length = 0;
+    static const bool ok = true;
+#if defined LIBO_INTERNAL_ONLY && HAVE_CXX14_CONSTEXPR
+    constexpr
+#endif
+    static bool isValid(char const (& literal)[1]) {
+        return literal[0] == '\0';
+    }
+#if defined LIBO_INTERNAL_ONLY
+    constexpr
+#endif
+    static char const * toPointer(char const (& literal)[1]) { return literal; }
+};
+#endif
+
 #if defined LIBO_INTERNAL_ONLY
 template<std::size_t N, typename T>
 struct ConstCharArrayDetector<sal_Unicode const [N], T> {