Fix swapping of vector elements

...which had been broken with edc85fb55f
"clang-tidy performance-unnecessary-copy-init in idl..reportdesign" (and could
cause "Tools - Options... - LibreOffice - Advanced - Java Options" to
erroneously list a single JRE multiple times, instead of listing different
JREs).

Change-Id: I6799903be39a5c6aa601131fad6eab3edea8d9e4
Reviewed-on: https://gerrit.libreoffice.org/73679
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

jvmfwk/plugins/sunmajor/pluginlib/util.cxx

@@ -731,8 +731,7 @@ void bubbleSortVersion(vector<rtl::Reference<VendorBase> >& vec)
             }
             if(nCmp == 1) // cur > next
             {
-                vec.at(j-1)= cur;
-                vec.at(j)= next;
+                std::swap(vec.at(j-1), vec.at(j));
             }
         }
         ++cIter;