It broke the build on the FreeBSD 10 buildbot, not sure why.
dnl CHECK STRUCTURES
dnl ----------------
dnl CHECK STRUCTURES
dnl ----------------
+dnl FIXME: This test could work on Linux if _BSD_SOURCE was #define'd
+dnl according to localtime(3).
+dnl
dnl For platforms such as FreeBSD that have tm_gmtoff in struct tm.
dnl (FreeBSD has a timezone() function but not a timezone global
dnl variable that is visible).
dnl For platforms such as FreeBSD that have tm_gmtoff in struct tm.
dnl (FreeBSD has a timezone() function but not a timezone global
dnl variable that is visible).
-dnl On Linux, $AM_CPPFLAGS contains -D_GNU_SOURCE, which makes
-dnl tm_gmtoff visible.
-nmh_saved_CPPFLAGS="$CPPFLAGS"
-CPPFLAGS="$AM_CPPFLAGS $CPPFLAGS"
-AC_CHECK_MEMBER([struct tm.tm_gmtoff],,,[[#include <time.h>]])
-CPPFLAGS="$nmh_saved_CPPFLAGS"
+AC_CHECK_MEMBERS([struct tm.tm_gmtoff],,,[#include <time.h>])