Fix -Wundef warnings in login/tst-utmp.c.

To remove -Wno-error=undef, we need to fix the remaining cases where
there are -Wundef warnings in the testsuite.  One of those places is
in login/tst-utmp.c.

When included from tst-utmpx.c, <utmpx.h> is included instead of
<utmp.h>, meaning the _HAVE_UT_* macros are not defined.  The test is
prepared for them not being defined, in that all the relevant
conditionals also include "defined UTMPX".  However, they test the
_HAVE_UT_* macros first, so resulting in -Wundef warnings.

This patch does the minimal fix of swapping the || operands.  This is
logically correct - avoiding checking a macro we know will not be
defined in the case where it is not defined.  It won't fix such
warnings for the case where the toplevel bits/utmp.h is used and most
_HAVE_UT_* aren't defined at all even when <utmp.h> is included, but
that case doesn't apply to any current glibc configuration.  Fixing it
would also be tricky in that, while glibc itself consistently uses
_HAVE_UT_* in ways that would work with 0 instead of undefined,
external packages that use the macros expect defined / undefined
instead of 1 / 0 (codesearch.debian.net shows uses by util-linux,
python-utmp, libsys-utmp-perl).

Tested for x86_64.

	* login/tst-utmp.c [_HAVE_UT_TYPE || defined UTMPX]: Change
	conditional to [defined UTMPX || _HAVE_UT_TYPE].
	[_HAVE_UT_TV || defined UTMPX]: Change conditional to [defined
	UTMPX || _HAVE_UT_TV].
	[_HAVE_UT_TV - 0 || defined UTMPX]: Change conditional to [defined
	UTMPX || _HAVE_UT_TV - 0].

2 files changed, 13 insertions, 4 deletions

diff --git a/ChangeLog b/ChangeLog
index 0daf15eeb9..da9a3e0851 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2015-08-19  Joseph Myers  <joseph@codesourcery.com>
+
+	* login/tst-utmp.c [_HAVE_UT_TYPE || defined UTMPX]: Change
+	conditional to [defined UTMPX || _HAVE_UT_TYPE].
+	[_HAVE_UT_TV || defined UTMPX]: Change conditional to [defined
+	UTMPX || _HAVE_UT_TV].
+	[_HAVE_UT_TV - 0 || defined UTMPX]: Change conditional to [defined
+	UTMPX || _HAVE_UT_TV - 0].
+
 2015-08-18  Joseph Myers  <joseph@codesourcery.com>
 
 	* sysdeps/mips/dl-machine.h [__mips_isa_rev < 6]: Change
diff --git a/login/tst-utmp.c b/login/tst-utmp.c
index 2f2da908ed..a69a556de5 100644
--- a/login/tst-utmp.c
+++ b/login/tst-utmp.c
@@ -39,7 +39,7 @@
 #endif
 
 
-#if _HAVE_UT_TYPE || defined UTMPX
+#if defined UTMPX || _HAVE_UT_TYPE
 
 /* Prototype for our test function.  */
 static int do_test (int argc, char *argv[]);
@@ -75,7 +75,7 @@ do_prepare (int argc, char *argv[])
 
 struct utmp entry[] =
 {
-#if _HAVE_UT_TV || defined UTMPX
+#if defined UTMPX || _HAVE_UT_TV
 #define UT(a)  .ut_tv = { .tv_sec = (a)}
 #else
 #define UT(a)  .ut_time = (a)
@@ -167,7 +167,7 @@ simulate_login (const char *line, const char *user)
 	    entry[n].ut_pid = (entry_pid += 27);
 	  entry[n].ut_type = USER_PROCESS;
 	  strncpy (entry[n].ut_user, user, sizeof (entry[n].ut_user));
-#if _HAVE_UT_TV - 0 || defined UTMPX
+#if defined UTMPX || _HAVE_UT_TV - 0
 	  entry[n].ut_tv.tv_sec = (entry_time += 1000);
 #else
           entry[n].ut_time = (entry_time += 1000);
@@ -201,7 +201,7 @@ simulate_logout (const char *line)
 	{
 	  entry[n].ut_type = DEAD_PROCESS;
 	  strncpy (entry[n].ut_user, "", sizeof (entry[n].ut_user));
-#if _HAVE_UT_TV - 0 || defined UTMPX
+#if defined UTMPX || _HAVE_UT_TV - 0
           entry[n].ut_tv.tv_sec = (entry_time += 1000);
 #else
           entry[n].ut_time = (entry_time += 1000);