[InstrProf][NFC] Remove stray option in InstrProfWriter

This variable was added to `InstrProfWriter.cpp`  in D115693 by mistake and it isn't needed.

Reviewed By: kyulee

Differential Revision: https://reviews.llvm.org/D118664

Author: Ellis Hoag

llvm/lib/ProfileData/InstrProfWriter.cpp

@@ -32,7 +32,6 @@
 #include <vector>
 
 using namespace llvm;
-extern cl::opt<bool> DebugInfoCorrelate;
 
 // A struct to define how the data stream should be patched. For Indexed
 // profiling, only uint64_t data type is needed.