Drop include for features.h

The following information is taken from the feature_test_macros man
page:

<features.h> is a Linux/glibc-specific header file.  Other systems have
an analogous file, but typically with a different name.  This header
file is automatically included by other header files as required: it is
not necessary to explicitly include it in order to employ feature test
macros.

Reported-by: Tibor Vago <tibor.vago@gmail.com>
X-Gentoo-Bug: 399635
X-Gentoo-Bug-URL: http://bugs.gentoo.org/show_bug.cgi?id=399635

src/rc/checkpath.c

@@ -32,7 +32,6 @@
 #include <sys/types.h>
 #include <sys/stat.h>
 
-#include <features.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <getopt.h>