vendor in a copy of GNU libtool to see if it will ease my libtool woes

also:
- make sure everything distcleans properly
- add files from newer upstream gdb sources

Change-Id: I3c4908d0d86b0e100b13421783aed2bec0c3c645
minor git hook tweak

Change-Id: I9f5089de297fb3f6fdfb49718a0c8ea1d01b6036