Refactor profile summary support code. NFC.

Summary computation is not just for instrumented profiling and so I have moved
the ProfileSummary class to ProfileCommon.h (named so to allow code unrelated
to summary but common to instrumented and sampled profiling to be placed there)

Differential Revision: http://reviews.llvm.org/D16661

llvm-svn: 259846
diff --git a/llvm/lib/ProfileData/CMakeLists.txt b/llvm/lib/ProfileData/CMakeLists.txt
index 22cca4b..c487cca 100644
--- a/llvm/lib/ProfileData/CMakeLists.txt
+++ b/llvm/lib/ProfileData/CMakeLists.txt
@@ -5,6 +5,7 @@
   CoverageMapping.cpp
   CoverageMappingWriter.cpp
   CoverageMappingReader.cpp
+  ProfileSummary.cpp
   SampleProf.cpp
   SampleProfReader.cpp
   SampleProfWriter.cpp