COMP: Use HAVE_SYS_PARAM_H properly in libtar

The value is computed by a try-compile for libtar.  This teaches the
sources to actually use the result.

Utilities/cmtar/append.c

@@ -18,8 +18,10 @@
 #if defined(_WIN32) && !defined(__CYGWIN__)
 # include <libtar/compat.h>
 #else
+# ifdef HAVE_SYS_PARAM_H
 #  include <sys/param.h>
 # endif
+#endif
 #include <libtar/compat.h>
 #include <sys/types.h>
 

Utilities/cmtar/decode.c

@@ -17,8 +17,10 @@
 #if defined(_WIN32) && !defined(__CYGWIN__)
 # include <libtar/compat.h>
 #else
+# ifdef HAVE_SYS_PARAM_H
 #  include <sys/param.h>
 # endif
+#endif
 
 #ifndef WIN32
 #include <pwd.h>

Utilities/cmtar/extract.c

@@ -28,8 +28,10 @@
 # include <direct.h>
 #else
 # include <utime.h>
+# ifdef HAVE_SYS_PARAM_H
 #  include <sys/param.h>
 # endif
+#endif
 
 #ifdef STDC_HEADERS
 # include <stdlib.h>

Utilities/cmtar/libtar.c

@@ -19,8 +19,10 @@
 #include <libtar/compat.h>
 #include <io.h>
 #else
+# ifdef HAVE_SYS_PARAM_H
 #  include <sys/param.h>
 # endif
+#endif
 
 #ifdef STDC_HEADERS
 # include <string.h>

Utilities/cmtar/util.c

@@ -23,8 +23,10 @@
 #if defined(_WIN32) && !defined(__CYGWIN__)
 #include <direct.h>
 #else
+# ifdef HAVE_SYS_PARAM_H
 #  include <sys/param.h>
 # endif
+#endif
 
 /* hashing function for pathnames */
 int