message: build: move rtc_prefer_fixed_point
  making it more visible where fixed point is preferred
  Cr-Commit-Position: refs/heads/master@{#32081}
diff: @@ -85,9 +85,6 @@ declare_args() {
  # library that comes with WebRTC (i.e. rtc_build_ssl == 0).
  rtc_ssl_root = ""
  - # Selects fixed-point code where possible.
  - rtc_prefer_fixed_point = false
  -
  # Enable when an external authentication mechanism is used for performing
  # packet authentication for RTP packets instead of libsrtp.
  rtc_enable_external_auth = build_with_chromium
  @@ -134,6 +131,8 @@ declare_args() {
  # See http://clang.llvm.org/docs/SanitizerCoverage.html .
  rtc_sanitize_coverage = ""
  + # Selects fixed-point code where possible.
  + rtc_prefer_fixed_point = false
  if (current_cpu == "arm" || current_cpu == "arm64") {
  rtc_prefer_fixed_point = true
  }
  