Revert "blockfreq: Rewrite BlockFrequencyInfoImpl" (#2)

This reverts commit r206622 and the MSVC fixup in r206626.

Apparently the remotely failing tests are still failing, despite my
attempt to fix the nondeterminism in r206621.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206628 91177308-0d34-0410-b5e6-96231b3b80d8
Fix uint -> size_t conversion warning.

This warning is disabled for the LLVM build,
but external users of the header can still
run into this.

Patch by Ke Bai

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206629 91177308-0d34-0410-b5e6-96231b3b80d8
Update comment in LLVMBitCodes.h to reflect the actual bitcode record

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206630 91177308-0d34-0410-b5e6-96231b3b80d8
Add range access to MCAssembler's symbol collection.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206631 91177308-0d34-0410-b5e6-96231b3b80d8