Fix XPASSing visit_format_arg.pass.cpp (#3357)

Author: StephanTLavavej

tests/libcxx/expected_results.txt

@@ -399,9 +399,6 @@ std/strings/basic.string/string.modifiers/robust_against_adl.pass.cpp FAIL
 # GH-3100: <memory> etc.: ADL should be avoided when calling _Construct_in_place and its friends
 std/utilities/function.objects/func.wrap/func.wrap.func/robust_against_adl.pass.cpp FAIL
 
-# GH-3336: Failure to format basic_string_view with non-standard traits
-std/utilities/format/format.arguments/format.arg/visit_format_arg.pass.cpp FAIL
-
 
 # *** CRT BUGS ***
 # We're permanently missing aligned_alloc().

tests/libcxx/skipped_tests.txt

@@ -399,9 +399,6 @@ strings\basic.string\string.modifiers\robust_against_adl.pass.cpp
 # GH-3100: <memory> etc.: ADL should be avoided when calling _Construct_in_place and its friends
 utilities\function.objects\func.wrap\func.wrap.func\robust_against_adl.pass.cpp
 
-# GH-3336: Failure to format basic_string_view with non-standard traits
-utilities\format\format.arguments\format.arg\visit_format_arg.pass.cpp
-
 
 # *** CRT BUGS ***
 # We're permanently missing aligned_alloc().