Add support to debugserver for some new ways to interact with dyld

to find the solibs loaded in a process.  Support two new ways of
sending the jGetLoadedDynamicLibrariesInfos packet to debugserver
and add a new jGetSharedCacheInfo packet.  Update the documentation
for these packets as well.  The changes to lldb to use these will
be a separate commit.

<rdar://problem/25251243> 

llvm-svn: 274718