message: [OpenCL] Fixes linking issue
  introduced linking issue that caused
  logging.cc:(.text+0xa64): undefined reference to
  `tensorflow::StringPiece::Hasher::operator()(tensorflow::StringPiece) const'
diff: @@ -76,6 +76,18 @@ toolchain {
  unfiltered_cxx_flag: "-D__TIMESTAMP__=\"redacted\""
  unfiltered_cxx_flag: "-D__TIME__=\"redacted\""
  + compiler_flag: "-fPIE"
  +
  + # Keep stack frames for debugging, even in opt mode.
  + compiler_flag: "-fno-omit-frame-pointer"
  +
  + # Anticipated future default.
  + linker_flag: "-no-canonical-prefixes"
  + unfiltered_cxx_flag: "-fno-canonical-system-headers"
  +
  + # Have gcc return the exit code from ld.
  + linker_flag: "-pass-exit-codes"
  +
  # All warnings are enabled. Maybe enable -Werror as well?
  compiler_flag: "-Wall"
  @@ -105,6 +117,9 @@ toolchain {
  compiler_flag: "-g0"
  compiler_flag: "-O2"
  compiler_flag: "-DNDEBUG"
  + compiler_flag: "-ffunction-sections"
  + compiler_flag: "-fdata-sections"
  + linker_flag: "-Wl,--gc-sections"
  }
  }
  