[maglev] Add to Linux64 bots

Run Maglev on the Linux64 bots -- eventually we'll want to move it to
the extra variant, but for now the flag is x64-only.

Bug: v8:7700, v8:12727
Change-Id: I8b8329720ac96ab1655aef9e210a52092f81cc91
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3752979
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Auto-Submit: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/main@{#81635}

infra/testing/builders.pyl

@@ -353,6 +353,8 @@
       {'name': 'v8testing', 'variant': 'stress_instruction_scheduling'},
       {'name': 'v8testing', 'variant': 'stress_concurrent_allocation'},
       {'name': 'v8testing', 'variant': 'stress_concurrent_inlining'},
+      # Maglev -- move to extra once more architectures are supported.
+      {'name': 'mjsunit', 'variant': 'maglev'},
     ],
   },
   'v8_linux64_dict_tracking_dbg_ng_triggered': {
@@ -475,6 +477,8 @@
       {'name': 'v8testing', 'variant': 'extra'},
       {'name': 'v8testing', 'variant': 'no_lfa'},
       {'name': 'v8testing', 'variant': 'stress_instruction_scheduling'},
+      # Maglev -- move to extra once more architectures are supported.
+      {'name': 'mjsunit', 'variant': 'maglev'},
     ],
   },
   'v8_linux64_perfetto_dbg_ng_triggered': {
@@ -520,6 +524,8 @@
       {'name': 'v8testing', 'variant': 'no_lfa'},
       {'name': 'v8testing', 'variant': 'slow_path'},
       {'name': 'v8testing', 'variant': 'stress_instruction_scheduling'},
+      # Maglev -- move to extra once more architectures are supported.
+      {'name': 'mjsunit', 'variant': 'maglev'},
     ],
   },
   'v8_linux64_tsan_rel_ng_triggered': {
@@ -1152,6 +1158,8 @@
       {'name': 'v8testing', 'variant': 'minor_mc'},
       {'name': 'v8testing', 'variant': 'no_lfa'},
       {'name': 'v8testing', 'variant': 'stress_instruction_scheduling'},
+      # Maglev -- move to extra once more architectures are supported.
+      {'name': 'mjsunit', 'variant': 'maglev'},
       # Noavx.
       {
         'name': 'mozilla',
@@ -1213,6 +1221,8 @@
       {'name': 'v8testing', 'variant': 'stress_instruction_scheduling'},
       {'name': 'v8testing', 'variant': 'stress_concurrent_allocation'},
       {'name': 'v8testing', 'variant': 'stress_concurrent_inlining'},
+      # Maglev -- move to extra once more architectures are supported.
+      {'name': 'mjsunit', 'variant': 'maglev'},
       # Noavx.
       {
         'name': 'mozilla',