[libcxx] [test] Remove UNSUPPORTED markings for mingw issues that no longer are present in CI

Differential Revision: https://reviews.llvm.org/D123146

Author: mstorsjo

libcxx/test/std/language.support/support.runtime/ctime.timespec.compile.pass.cpp

@@ -17,12 +17,6 @@
 // unavailable until macOS 10.15
 // XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx10.{{9|10|11|12|13|14}}
 
-// MinGW used to lack timespec_get, but has got it in newer versions.
-// Mark the test as unsupported for a transition period, to avoid spurious
-// failures when upgrading the precommit testing environment. After
-// the testing environment is upgraded, we could remove the marking altogether.
-// UNSUPPORTED: target={{.+}}-windows-gnu
-
 #include <ctime>
 #include <type_traits>
 

libcxx/test/std/thread/thread.threads/thread.thread.class/thread.thread.constr/F.pass.cpp

@@ -15,12 +15,6 @@
 // UNSUPPORTED: libcpp-has-no-threads
 // UNSUPPORTED: sanitizer-new-delete
 
-// This fails on MinGW when statically linked, if built with Clang 13 or older.
-// (It's fixed in the upcoming Clang 14, by https://reviews.llvm.org/D109651.)
-// Prior to the fix, when statically linked, the unwind info for the two
-// (default and overridden) operator new implementations clash.
-// UNSUPPORTED: target={{.+}}-windows-gnu && !windows-dll && clang-13
-
 #include <thread>
 #include <new>
 #include <atomic>