loplugin:stringadd in registry..sal

after my patch to merge the bufferadd loplugin into stringadd

Change-Id: I1658b960d44780f7d9c447246b1178cb70be5e66
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/149581
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>

registry/source/regimpl.cxx

@@ -643,8 +643,7 @@ RegError ORegistry::createKey(RegKeyHandle hKey, std::u16string_view keyName,
                 return RegError::CREATE_KEY_FAILED;
             }
 
-            sFullPath.append(token);
-            sFullPath.append('/');
+            sFullPath.append(token + "/");
         }
     } while(nIndex != -1);
 

reportdesign/source/ui/dlg/Navigator.cxx

@@ -82,16 +82,14 @@ static OUString lcl_getName(const uno::Reference< beans::XPropertySet>& _xElemen
     uno::Reference< report::XReportControlModel> xReportModel(_xElement,uno::UNO_QUERY);
     if ( xFixedText.is() )
     {
-        sName.append(" : ");
-        sName.append(xFixedText->getLabel());
+        sName.append(" : " + xFixedText->getLabel());
     }
     else if ( xReportModel.is() && _xElement->getPropertySetInfo()->hasPropertyByName(PROPERTY_DATAFIELD) )
     {
         ReportFormula aFormula( xReportModel->getDataField() );
         if ( aFormula.isValid() )
         {
-            sName.append(" : ");
-            sName.append( aFormula.getUndecoratedContent() );
+            sName.append(" : " + aFormula.getUndecoratedContent() );
         }
     }
     return sName.makeStringAndClear();

sal/osl/unx/file_url.cxx

@@ -955,8 +955,7 @@ oslFileError osl::detail::convertPathnameToUrl(OString const & pathname, OUStrin
             static sal_Unicode const aHex[16]
                 = { 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39,
                     0x41, 0x42, 0x43, 0x44, 0x45, 0x46 }; /* '0'--'9', 'A'--'F' */
-            buf.append(aHex[c >> 4]);
-            buf.append(aHex[c & 15]);
+            buf.append(OUStringChar(aHex[c >> 4]) + OUStringChar(aHex[c & 15]));
             --convert;
             continue;
         }

sal/rtl/uri.cxx

@@ -143,7 +143,7 @@ sal_uInt32 readUcs4(sal_Unicode const ** pBegin, sal_Unicode const * pEnd,
         }
         else
         {
-            OStringBuffer aBuf;
+            OStringBuffer aBuf(16);
             aBuf.append(static_cast< char >(nChar));
             rtl_TextToUnicodeConverter aConverter
                 = rtl_createTextToUnicodeConverter(eCharset);