В их репозитории как раз и лежит Dropbox integration for nautilus (nautilus-dropbox), который очень редко обновляется (это всего-лишь меню для nautilus).

Чтобы обновить сам бинарный клиент Dropbox`а, достаточно выполнить следующие команды в терминале:
$ dropbox stop
$ dropbox status #Должно высветится «not running»
$ rm -r ~/.dropbox-dist/
$ dropbox start -i

После чего бинарный клиент будет скачан последней версии.

А в директории .libs/ смотрели?

unreturned@kovalkov:/tmp/reailip2$ sudo apxs2 -c mod_realip2.c 
Use of uninitialized value $includedir in concatenation (.) or string at (eval 9) line 1.
/usr/share/apr-1.0/build/libtool --silent --mode=compile --tag=disable-static x86_64-linux-gnu-gcc -prefer-pic -DLINUX=2 -D_FORTIFY_SOURCE=2 -D_GNU_SOURCE -D_REENTRANT -I/usr/include -I/usr/include/apr-1.0 -I/usr/include/openssl -I/usr/include/xmltok -pthread  -DLINUX=2 -D_FORTIFY_SOURCE=2 -D_GNU_SOURCE -D_REENTRANT -I -I. -I/usr/include -I/usr/include/apr-1.0     -I/usr/include/apache2  -I/usr/include/apr-1.0   -I/usr/include/apr-1.0 -I/usr/include  -c -o mod_realip2.lo mod_realip2.c && touch mod_realip2.slo
/usr/share/apr-1.0/build/libtool --silent --mode=link --tag=disable-static x86_64-linux-gnu-gcc -Wl,--as-needed -Wl,-z,relro   -o mod_realip2.la  -rpath /usr/lib/apache2/modules -module -avoid-version    mod_realip2.lo
unreturned@kovalkov:/tmp/reailip2$ ls -all
total 28
drwxr-xr-x 3 unreturned unreturned 4096 Jan 18 01:46 .
drwxrwxrwt 6 root       root       4096 Jan 18 01:46 ..
drwxr-xr-x 2 root       root       4096 Jan 18 01:46 .libs
-rw-r--r-- 1 unreturned unreturned 6243 Jan 18 01:46 mod_realip2.c
-rw-r--r-- 1 root       root        949 Jan 18 01:46 mod_realip2.la
-rw-r--r-- 1 root       root        291 Jan 18 01:46 mod_realip2.lo
-rw-r--r-- 1 root       root          0 Jan 18 01:46 mod_realip2.slo
unreturned@kovalkov:/tmp/reailip2$ cd .libs/
unreturned@kovalkov:/tmp/reailip2/.libs$ ls -all
total 36
drwxr-xr-x 2 root       root        4096 Jan 18 01:46 .
drwxr-xr-x 3 unreturned unreturned  4096 Jan 18 01:46 ..
lrwxrwxrwx 1 root       root          17 Jan 18 01:46 mod_realip2.la -> ../mod_realip2.la
-rw-r--r-- 1 root       root         950 Jan 18 01:46 mod_realip2.lai
-rw-r--r-- 1 root       root        6224 Jan 18 01:46 mod_realip2.o
-rwxr-xr-x 1 root       root       13556 Jan 18 01:46 mod_realip2.so
unreturned@kovalkov:/tmp/reailip2/.libs$ cd ../

Также, произвести сразу установку модуля можно добавлением флага -i

sudo apxs2 -c -i mod_realip2.c 
Use of uninitialized value $includedir in concatenation (.) or string at (eval 9) line 1.
/usr/share/apr-1.0/build/libtool --silent --mode=compile --tag=disable-static x86_64-linux-gnu-gcc -prefer-pic -DLINUX=2 -D_FORTIFY_SOURCE=2 -D_GNU_SOURCE -D_REENTRANT -I/usr/include -I/usr/include/apr-1.0 -I/usr/include/openssl -I/usr/include/xmltok -pthread  -DLINUX=2 -D_FORTIFY_SOURCE=2 -D_GNU_SOURCE -D_REENTRANT -I -I. -I/usr/include -I/usr/include/apr-1.0     -I/usr/include/apache2  -I/usr/include/apr-1.0   -I/usr/include/apr-1.0 -I/usr/include  -c -o mod_realip2.lo mod_realip2.c && touch mod_realip2.slo
/usr/share/apr-1.0/build/libtool --silent --mode=link --tag=disable-static x86_64-linux-gnu-gcc -Wl,--as-needed -Wl,-z,relro   -o mod_realip2.la  -rpath /usr/lib/apache2/modules -module -avoid-version    mod_realip2.lo
/usr/share/apache2/build/instdso.sh SH_LIBTOOL='/usr/share/apr-1.0/build/libtool' mod_realip2.la /usr/lib/apache2/modules
/usr/share/apr-1.0/build/libtool --mode=install cp mod_realip2.la /usr/lib/apache2/modules/
libtool: install: cp .libs/mod_realip2.so /usr/lib/apache2/modules/mod_realip2.so
libtool: install: cp .libs/mod_realip2.lai /usr/lib/apache2/modules/mod_realip2.la
libtool: finish: PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/sbin" ldconfig -n /usr/lib/apache2/modules
----------------------------------------------------------------------
Libraries have been installed in:
   /usr/lib/apache2/modules

If you ever happen to want to link against installed libraries
in a given directory, LIBDIR, you must either use libtool, and
specify the full pathname of the library, or use the `-LLIBDIR'
flag during linking and do at least one of the following:
   - add LIBDIR to the `LD_LIBRARY_PATH' environment variable
     during execution
   - add LIBDIR to the `LD_RUN_PATH' environment variable
     during linking
   - use the `-Wl,-rpath -Wl,LIBDIR' linker flag
   - have your system administrator add LIBDIR to `/etc/ld.so.conf'

See any operating system documentation about shared libraries for
more information, such as the ld(1) and ld.so(8) manual pages.
----------------------------------------------------------------------
chmod 644 /usr/lib/apache2/modules/mod_realip2.so