X87:[test] Disables 2 test cases for x87.

  The reason:
  The CL #40862 (https://codereview.chromium.org/2433093002 ) caused 2 test cases failed for X87.
  Because Both 2 test cases (MoveOptimizerTest.RemovesRedundantExplicit and RegisterAllocatorTest.CanAllocateFPRegisters)
  needs 2 allocatable Float/Double registers.
  But there's only 1 allocatable Float/Double register in x87 turbofan compiler, i.e.: register index 0.

  This CL disables MoveOptimizerTest.RemovesRedundantExplicit and RegisterAllocatorTest.CanAllocateFPRegisters test cases for x87.

BUG=

Review-Url: https://codereview.chromium.org/2520623005
Cr-Commit-Position: refs/heads/master@{#41131}

test/unittests/unittests.status

@@ -9,6 +9,8 @@
   'Ieee754.Tan': [SKIP],
   'Ieee754.Acosh': [SKIP],
   'Ieee754.Asinh': [SKIP],
+  'MoveOptimizerTest.RemovesRedundantExplicit': [SKIP],
+  'RegisterAllocatorTest.CanAllocateFPRegisters': [SKIP],
 }],  # 'arch == x87'
 
 ['variant == asm_wasm', {