check-clang-tools: Introduce the feature "target-headers".

For now, it just detects that host is non-Windows and target is msvc.

FIXME: It should be probable for cross compilations. Detect whether target's headers would be available.
llvm-svn: 261814

clang-tools-extra/test/clang-tidy/modernize-deprecated-headers-cxx03.cpp

@@ -1,4 +1,5 @@
 // RUN: %check_clang_tidy %s modernize-deprecated-headers %t -- -- -std=c++03 -isystem %S/Inputs/Headers
+// REQUIRES: target-headers
 
 #include <assert.h>
 #include <complex.h>

clang-tools-extra/test/clang-tidy/modernize-deprecated-headers-cxx11.cpp

@@ -1,4 +1,5 @@
 // RUN: %check_clang_tidy %s modernize-deprecated-headers %t -- -- -std=c++11 -isystem %S/Inputs/Headers
+// REQUIRES: target-headers
 
 #include <assert.h>
 #include <complex.h>

clang-tools-extra/test/lit.cfg

@@ -189,6 +189,12 @@ if not platform.system() in ['Windows'] or not execute_external:
 if platform.system() not in ['Windows']:
     config.available_features.add('ansi-escape-sequences')
 
+# Set if default-target's system headers available.
+# For example in general, MS headers are supposed unavailable on non-Windows hosts.
+# FIXME: It should be probable for cross compilations.
+if not (platform.system() not in ['Windows'] and re.match(r'.*-win32$', config.target_triple)):
+    config.available_features.add('target-headers')
+
 check_clang_tidy = os.path.join(
     config.test_source_root, "clang-tidy", "check_clang_tidy.py")
 config.substitutions.append(