idl: avoid -Werror=deprecated-copy (GCC trunk towards GCC 9)

...by removing explicitly user-provided functions that do the same as their
implicitly-defined counterparts, but may prevent implicitly declared copy
functions from being defined as non-deleted in the future

Change-Id: I75e356ee9e12bb2d88ed9db6c60c49b3f4ac5d58
Reviewed-on: https://gerrit.libreoffice.org/58056
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

idl/inc/database.hxx

@@ -44,13 +44,6 @@ public:
     const OString&  GetText() const { return aText; }
     void            SetText( const OString& rT ) { aText = rT; }
     bool            IsError() const { return nLine != 0; }
-    SvIdlError &    operator = ( const SvIdlError & rRef )
-                    {
-                        aText   = rRef.aText;
-                        nLine   = rRef.nLine;
-                        nColumn = rRef.nColumn;
-                        return *this;
-                    }
 };
 
 class SvParseException : public std::exception