InstrProf: Remove CoverageMapping::HasCodeBefore, it isn't used

It's not entirely clear to me what this field was meant for, but it's
always false. Remove it.

llvm-svn: 228034

llvm/lib/ProfileData/CoverageMappingWriter.cpp

@@ -172,11 +172,7 @@ void CoverageMappingWriter::write(raw_ostream &OS) {
     }
     assert(I->LineStart >= PrevLineStart);
     encodeULEB128(I->LineStart - PrevLineStart, OS);
-    uint64_t CodeBeforeColumnStart =
-        uint64_t(I->HasCodeBefore) |
-        (uint64_t(I->ColumnStart)
-         << CounterMappingRegion::EncodingHasCodeBeforeBits);
-    encodeULEB128(CodeBeforeColumnStart, OS);
+    encodeULEB128(I->ColumnStart, OS);
     assert(I->LineEnd >= I->LineStart);
     encodeULEB128(I->LineEnd - I->LineStart, OS);
     encodeULEB128(I->ColumnEnd, OS);