Hopefully unbreaks compiler-rt build on linux.

llvm-svn: 164025

With the advent of the __llvm_gcov_flush function, we need to be able to merge
counts into the .gcda files in an intelligent manner. This involves reading the
file if it exists, adding the counts together, and then writing the results.
<rdar://problem/12185886>

llvm-svn: 163923

llvm-svn: 157600

llvm-svn: 157573

- Add memcpy and memcmp to the stub headers.
- __uint128_t is not available on 32 bit platforms. It's also unused so just
  comment it out for now.

llvm-svn: 153779

llvm-svn: 146188

the main compiler-rt and profile modules, at least on x86.

llvm-svn: 146131

 - Motivation is explained in the README, but basically it is convenient to be
   able to build compiler-rt free standing. Since our external dependencies are
   so small, we can achieve this relatively easily by just stubbing out the
   declarations of the external dependencies.
 - This is in no way, shape, or form intended to be complete, it is just the
   minimal stubs necessary to support the stuff we use.

llvm-svn: 144843