include errno.h instead of argp.h

[Chen Qi <Qi.Chen@windriver.com>]

configure should include errno.h instead of argp.h when
checking for presence of program_invocation_short_name
uclibc defines this to be const char* unlike util-linux-ng
which defines this to be char* so this error goes unnoticed
on glibc/eglibc systems.

here is the error it fixes

in file included from mountP.h:14:0,                                                                               
                 from cache.c:29:                                                                                  
/home/kraj/work/slugos/build/tmp-slugos-uclibc/sysroots/nslu2le/usr/include/errno.h:55:46: error: conflicting types for '__progname'                                                                                                  
../../../include/c.h:118:14: note: previous declaration of '__progname' was here                                   
make[3]: *** [cache.lo] Error 1          


Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Jonathan Liu <net147@gmail.com>

Index: util-linux-2.22.1/configure.ac
===================================================================
--- util-linux-2.22.1.orig/configure.ac
+++ util-linux-2.22.1/configure.ac
@@ -372,7 +372,7 @@ esac
 
 AC_MSG_CHECKING([whether program_invocation_short_name is defined])
 AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
-	#include <argp.h>
+	#include <errno.h>
 ]], [[
 	program_invocation_short_name = "test";
 ]])], [