svn merge --ignore-ancestry -r 58273:58283...

svn merge --ignore-ancestry -r 58273:58283 svn+ssh://svn.lindenlab.com/svn/linden/branches/maintenance

The diff is basically a no-op since it's a reverse-merge from release itself. However, several things tried to come along for the ride, so I inspected them carefully:

* Reverted libcurl changes which tried to migrate back from maintenance (see r58322)
* Reverted debugging output in lltooldraganddrop.cpp, which had been added then removed again
* Reverted false-positive binary conflict in libgtk-x11-2.0.so
* Reverted false-positive whitespace (?) conflicts in llmail.cpp, and lldataconnector.cpp
* Left a whitespace change in llselectmgr.cpp so there was something to commit