adjust wording of error message in LinuxKernelSymbols.cpp
adjust wording of error message in LinuxKernelSymbols.cpp

HPCToolkit/hpctoolkit,HPCToolkit/hpctoolkit,HPCToolkit/hpctoolkit,HPCToolkit/hpctoolkit,HPCToolkit/hpctoolkit,HPCToolkit/hpctoolkit