After RTFM (debian/README.source from the source tree, which references the excellent /usr/share/doc/quilt/README.source) I got a handle on the patch system and put together a less messy and more precise patch:
099_pam_limits_include_rttime_nrlimits16.patch Index: pam-1.1.2/modules/pam_limits/pam_limits.c =================================================================== --- pam-1.1.2.orig/modules/pam_limits/pam_limits.c 2011-05-24 12:01:59.000000000 -0400 +++ pam-1.1.2/modules/pam_limits/pam_limits.c 2011-05-24 12:24:29.000000000 -0400 @@ -30,6 +30,14 @@ #include <sys/types.h> #include <sys/stat.h> #include <sys/resource.h> + +// Temporary workaround for #627619, #625226 +#ifndef RLIMIT_RTTIME +#define RLIMIT_RTTIME 15 +#undef RLIM_NLIMITS +#define RLIM_NLIMITS 16 +#endif + #include <limits.h> #include <glob.h> #include <utmp.h> After inserting the patch in the quilt series and doing: dpkg-buildpackage -b > ./dpkg-buildpackage.log 2>&1 (having a log of the output of 'dpkg-buildpackage' process proved very instructive), then pointing the /etc/pam.d/ files to the new pam_limits.so, 'Max realtime timeout' is recognized.
