Add support for "platform" configurations, which define a suite of compiler-rt
libraries to generate.
 - Each library may be built with different flags and for different
   architectures, and there is support for building Darwin style fat archives.

 - Uses an ambituous amount of make programming, but should be hidden to
   users and developers.

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@93720 91177308-0d34-0410-b5e6-96231b3b80d8
13 files changed