Fix German comment translation

This is a minor fix to the German comment translation made on the
commit 5ddef164
(https://gerrit.libreoffice.org/35343). Specifically, it is a fix
according to the comment in
https://gerrit.libreoffice.org/#/c/35343/6/sc/source/ui/docshell/docsh8.cxx

Change-Id: I7462de4589856a58fda58d52583a0702ddec0a0d
Reviewed-on: https://gerrit.libreoffice.org/35928Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Michael Stahl <mstahl@redhat.com>

sc/source/ui/docshell/docsh8.cxx

@@ -958,7 +958,7 @@ sal_uLong ScDocShell::DBaseExport( const OUString& rFullFileName, rtl_TextEncodi
                     case sdbc::DataType::DATE:
                         {
                             aDocument.GetValue( nDocCol, nDocRow, nTab, fVal );
-                            // no value differentiation between 0 with value and 0 no-value
+                            // differentiate between 0 with value and 0 no-value
                             bool bIsNull = (fVal == 0.0);
                             if ( bIsNull )
                                 bIsNull = !aDocument.HasValueData( nDocCol, nDocRow, nTab );