Add the `__memprof_default_options_str` variable, initialized via the `-memprof-runtime-default-options` LLVM flag, to hold the default options string for memprof. This allows us to set these options during compile time in the clang invocation. Also update the docs to describe the various ways to set these options.
Compiler-RT ================================ This directory and its subdirectories contain source code for the compiler support routines. Compiler-RT is open source software. You may freely distribute it under the terms of the license agreement found in LICENSE.txt. ================================