Also silent -Wno-cast-qual in the SWIG Python wrapper. Remove a huge number of warnings

git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@195930 91177308-0d34-0410-b5e6-96231b3b80d8
Update gitignore to be effective.
Stop to try to rebuild llvm/clang everytime.
The output archive list contains libLLVMArchive.a which does not exist anymore.
ranlib is useless when using libtool.
Factorize build settings in external xcconfig files.
Doing this greatly reduces the number of duplicated settings, as 'SDK' specific settings can be specified only once instead of once per Build Configuration.

This also fix a couple of issues with 10.9 SDK and python (which was already fixed for some targets but not all).
Project cleanup
Dead include and comments.
assert(0) => llvm_unreachable
Replace Host md5 cli invocation by a sane implementation based on modern Security functions.
"is platform" should not be part of the parent class.
Split GDBCommunication client into Process/Platform client.
This reduce platform dependencies on Process/Thread and many other components.
Remove dead argument from GDBRemoteCommunication constructor.
Move Server specific code into GDBRemoteServer class.
Split GDBCommunicationServer into Process and Platform specific classes.
Explode lldb-core into many smaller static libraries.
This greatly reduce the rebuild time when changing few files.
Add debugger packages support.
Useful args from debugserver

Summary:

Reviewers:

CC: