Check for availability of `cpio` command.

cpio may not be available on Windows, so it is better to check
for availability before running the command in a test.

llvm-svn: 278249

lld/test/ELF/reproduce-windows.s

@@ -1,4 +1,4 @@
-# REQUIRES: x86
+# REQUIRES: x86, cpio
 
 # Test that a repro archive always uses / instead of \.
 # RUN: rm -rf %t.dir

lld/test/ELF/reproduce.s

@@ -1,4 +1,4 @@
-# REQUIRES: x86
+# REQUIRES: x86, cpio
 
 # Extracting the cpio archive can get over the path limit on windows.
 # REQUIRES: shell

lld/test/lit.cfg

@@ -252,3 +252,7 @@ if cvtres and rc:
 # Check if "lib.exe" command exists.
 if lit.util.which('lib', config.environment['PATH']):
     config.available_features.add('winlib')
+
+# Check if "cpio" command exists.
+if lit.util.which('cpio', config.environment['PATH']):
+    config.available_features.add('cpio')