[libc++] Make the verify-support feature implicit

Tests that require support for Clang-verify are already marked as such
explicitly by their extension, which is .verify.cpp. Requiring the use
of an explicit Lit feature is, after thought, not really helpful.

This is a change in design: we have been bitten in the past by tests not
being enabled when we thought they were. However, the issue was mostly
with file extensions being ignored. The fix for that is not to blindly
require explicit features all the time, but instead to report all files
that are in the suite but that don't match any known test format. This
can be implemented in a follow-up patch.

Author: ldionne

libcxx/test/libcxx/algorithms/alg.modifying.operations/alg.random.shuffle/random_shuffle.depr_in_cxx14.verify.cpp

@@ -19,7 +19,6 @@
 
 // UNSUPPORTED: clang-4.0
 // UNSUPPORTED: c++98, c++03, c++11
-// REQUIRES: verify-support
 
 // ADDITIONAL_COMPILE_FLAGS: -D_LIBCPP_ENABLE_CXX17_REMOVED_RANDOM_SHUFFLE
 

libcxx/test/libcxx/atomics/diagnose_invalid_memory_order.verify.cpp

@@ -10,7 +10,7 @@
 // when -fdelayed-template-parsing is enabled, like it is on Windows.
 // XFAIL: LIBCXX-WINDOWS-FIXME
 
-// REQUIRES: verify-support, diagnose-if-support
+// REQUIRES: diagnose-if-support
 // UNSUPPORTED: libcpp-has-no-threads
 
 // <atomic>

libcxx/test/libcxx/containers/associative/non_const_comparator.incomplete.verify.cpp

@@ -7,7 +7,6 @@
 //===----------------------------------------------------------------------===//
 
 // UNSUPPORTED: c++98, c++03
-// REQUIRES: verify-support
 
 // Test that libc++ does not generate a warning diagnostic about the comparator
 // too early for containers of incomplete types.

libcxx/test/libcxx/containers/associative/non_const_comparator.verify.cpp

@@ -7,7 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 // UNSUPPORTED: c++98, c++03
-// REQUIRES: diagnose-if-support, verify-support
+// REQUIRES: diagnose-if-support
 
 // Test that libc++ generates a warning diagnostic when the container is
 // provided a non-const callable comparator.

libcxx/test/libcxx/containers/unord/non_const_comparator.incomplete.verify.cpp

@@ -7,7 +7,6 @@
 //===----------------------------------------------------------------------===//
 
 // UNSUPPORTED: c++98, c++03
-// REQUIRES: verify-support
 
 // Test that libc++ does not generate a warning diagnostic about the comparator
 // or the hasher too early for containers of incomplete types.

libcxx/test/libcxx/containers/unord/non_const_comparator.verify.cpp

@@ -7,7 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 // UNSUPPORTED: c++98, c++03
-// REQUIRES: diagnose-if-support, verify-support
+// REQUIRES: diagnose-if-support
 
 // Test that libc++ generates a warning diagnostic when the container is
 // provided a non-const callable comparator or a non-const hasher.

libcxx/test/libcxx/depr/depr.auto.ptr/auto.ptr/auto_ptr.depr_in_cxx11.verify.cpp

@@ -20,7 +20,6 @@
 
 // UNSUPPORTED: clang-4.0
 // UNSUPPORTED: c++98, c++03
-// REQUIRES: verify-support
 
 // ADDITIONAL_COMPILE_FLAGS: -D_LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR
 

libcxx/test/libcxx/depr/depr.c.headers/no_fgetpos_fsetpos.verify.cpp

@@ -6,7 +6,6 @@
 //
 //===----------------------------------------------------------------------===//
 
-// REQUIRES: verify-support
 // UNSUPPORTED: c++98 || c++03
 
 #include <cstdio>

libcxx/test/libcxx/depr/depr.default.allocator/allocator.members/address.depr_in_cxx17.verify.cpp

@@ -15,7 +15,6 @@
 // Deprecated in C++17
 
 // UNSUPPORTED: c++98, c++03, c++11, c++14
-// REQUIRES: verify-support
 
 // ADDITIONAL_COMPILE_FLAGS: -D_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS
 

libcxx/test/libcxx/depr/depr.default.allocator/allocator.members/allocate.cxx2a.verify.cpp

@@ -7,7 +7,6 @@
 //===----------------------------------------------------------------------===//
 
 // UNSUPPORTED: c++98, c++03, c++11, c++14, c++17
-// REQUIRES: verify-support
 
 // <memory>