Tests to move between size pools are flaky on Windows too [ci skip]

Needs more investigations.

test/ruby/test_gc_compact.rb

@@ -310,6 +310,7 @@ class TestGCCompact < Test::Unit::TestCase
 
   def test_moving_arrays_down_size_pools
     omit if GC::INTERNAL_CONSTANTS[:SIZE_POOL_COUNT] == 1
+    pend "Flaky on some platforms" if /solaris|mswin/i =~ RUBY_PLATFORM
 
     assert_separately(%w[-robjspace], "#{<<~"begin;"}\n#{<<~"end;"}", timeout: 10, signal: :SEGV)
     begin;
@@ -330,6 +331,7 @@ class TestGCCompact < Test::Unit::TestCase
 
   def test_moving_arrays_up_size_pools
     omit if GC::INTERNAL_CONSTANTS[:SIZE_POOL_COUNT] == 1
+    pend "Flaky on some platforms" if /solaris|mswin/i =~ RUBY_PLATFORM
 
     assert_separately(%w[-robjspace], "#{<<~"begin;"}\n#{<<~"end;"}", timeout: 10, signal: :SEGV)
     begin;
@@ -352,7 +354,7 @@ class TestGCCompact < Test::Unit::TestCase
 
   def test_moving_objects_between_size_pools
     omit if GC::INTERNAL_CONSTANTS[:SIZE_POOL_COUNT] == 1
-    omit "Flaky on Solaris" if /solaris/i =~ RUBY_PLATFORM
+    pend "Flaky on some platforms" if /solaris|mswin/i =~ RUBY_PLATFORM
 
     assert_separately(%w[-robjspace], "#{<<~"begin;"}\n#{<<~"end;"}", timeout: 10, signal: :SEGV)
     begin;
@@ -383,6 +385,7 @@ class TestGCCompact < Test::Unit::TestCase
 
   def test_moving_strings_up_size_pools
     omit if GC::INTERNAL_CONSTANTS[:SIZE_POOL_COUNT] == 1
+    pend "Flaky on some platforms" if /solaris|mswin/i =~ RUBY_PLATFORM
 
     assert_separately(%w[-robjspace], "#{<<~"begin;"}\n#{<<~"end;"}", timeout: 10, signal: :SEGV)
     begin;
@@ -402,6 +405,7 @@ class TestGCCompact < Test::Unit::TestCase
 
   def test_moving_strings_down_size_pools
     omit if GC::INTERNAL_CONSTANTS[:SIZE_POOL_COUNT] == 1
+    pend "Flaky on some platforms" if /solaris|mswin/i =~ RUBY_PLATFORM
 
     assert_separately(%w[-robjspace], "#{<<~"begin;"}\n#{<<~"end;"}", timeout: 10, signal: :SEGV)
     begin;
@@ -425,7 +429,7 @@ class TestGCCompact < Test::Unit::TestCase
     # This test fails on Solaris SPARC with the following error and I can't figure out why:
     #   TestGCCompact#test_moving_hashes_down_size_pools
     #   Expected 499 to be >= 500.
-    omit if /sparc-solaris/ =~ RUBY_PLATFORM
+    pend "Flaky on some platforms" if /solaris|mswin/i =~ RUBY_PLATFORM
 
     assert_separately(%w[-robjspace], "#{<<~"begin;"}\n#{<<~"end;"}", timeout: 10, signal: :SEGV)
     begin;