Fix regression in bubbleSortVersion

...introduced with 789055bc "clang-tidy
performance-unnecessary-copy-initialization" (so partially revert it).  Whatever
clang-tidy erroneously reported there, cur and next are lvalue references into
vec, so this attempted copy now actually overwrote one with the other.  The
result was that if multiple JREs are detected on the system, "Options -
LibreOffice - Advanced" would list a single one multiple times.

Change-Id: I7ef454c0f37669722812383848602dc2bacf7cd1
(cherry picked from commit 36a329b6)
Reviewed-on: https://gerrit.libreoffice.org/30923Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

jvmfwk/plugins/sunmajor/pluginlib/util.cxx

@@ -731,8 +731,9 @@ void bubbleSortVersion(vector<rtl::Reference<VendorBase> >& vec)
             }
             if(nCmp == 1) // cur > next
             {
+                rtl::Reference<VendorBase> less = next;
                 vec.at(j-1)= cur;
-                vec.at(j)= next;
+                vec.at(j)= less;
             }
         }
         ++cIter;