If the only version of sys-libs/db that you have installed is the new 4.5 version, then the configure script with subversion-1.4.3 won't detect it. This same bug has already been reported for ruby, openoffice, and apr-util; you might want to look at the related bugs: 169526 169587 169507 The config dies with: checking for socket in -lsocket... no checking for availability of Berkeley DB... no configure: error: Berkeley DB 4.0.14 wasn't found. I'll provide more information if it's helpful, but I don't want to clutter up the bug report with useless junk.
This is not a subversion bug, you need to recompile dev-libs/apr-util (which will likely fail, see Bug 169507). *** This bug has been marked as a duplicate of bug 136654 ***