chromium{Beta,Dev}: Fix a build error by disabling PGO

This fixes build errors like this:
error: Could not read profile ../../chrome/build/pgo_profiles/chrome-linux-4951-1649181099-528ef6669805f2d3db6f3ad7429cfa57a6078271.profdata: unsupported instrumentation profile format version

We already package the most recent stable LLVM version for Chromium but Google
relies on unreleased (Git) versions (thanks...). This isn't ideal but I
don't have the time to package yet another LLVM version so it'll have to
cut it for now.

See build/config/compiler/pgo/pgo.gni:
- 0 : Means that PGO is turned off.
- 1 : Used during the PGI (instrumentation) phase.
- 2 : Used during the PGO (optimization) phase.

With is_official_build the default is chrome_pgo_phase = 2.

pkgs/applications/networking/browsers/chromium/common.nix

@@ -279,6 +279,9 @@ let
       enable_widevine = true;
       # Provides the enable-webrtc-pipewire-capturer flag to support Wayland screen capture:
       rtc_use_pipewire = true;
+    } // optionalAttrs (chromiumVersionAtLeast "101") {
+      # Disable PGO because the profile data requires a newer compiler version (LLVM 14 isn't sufficient):
+      chrome_pgo_phase = 0;
     } // optionalAttrs proprietaryCodecs {
       # enable support for the H.264 codec
       proprietary_codecs = true;