Modernize and clean spec file

- Unify spaces/tabs to spaces
- Use autosetup/autopatch, get rid of explicit patch numbers

at.spec

@@ -15,23 +15,23 @@ Source1:	pam_atd
 Source3:    atd.sysconf
 Source5:    atd.systemd
 
-Patch0:		at-aarch64.patch
-Patch1:		at-3.1.18-make.patch
-Patch2:		at-3.1.20-pam.patch
-Patch4:		at-3.1.14-opt_V.patch
-Patch5:		at-3.1.20-shell.patch
-Patch6:		at-3.1.18-nitpicks.patch
-Patch8:		at-3.1.14-fix_no_export.patch 
-Patch9:		at-3.1.14-mailwithhostname.patch
-Patch10:	at-3.1.14-usePOSIXtimers.patch
-Patch12:	at-3.1.20-aborted-jobs.patch
-Patch13:	at-3.1.18-noabort.patch
-Patch14:	at-3.1.16-fclose-error.patch
-Patch15:	at-3.1.16-clear-nonjobs.patch
-Patch16:	at-3.1.18-utc-dst.patch
-Patch17:	at-3.1.20-lock-locks.patch
-Patch18:	at-3.1.23-document-n.patch
-Patch19:	at-3.1.20-log-jobs.patch
+Patch:      at-aarch64.patch
+Patch:      at-3.1.18-make.patch
+Patch:      at-3.1.20-pam.patch
+Patch:      at-3.1.14-opt_V.patch
+Patch:      at-3.1.20-shell.patch
+Patch:      at-3.1.18-nitpicks.patch
+Patch:      at-3.1.14-fix_no_export.patch
+Patch:      at-3.1.14-mailwithhostname.patch
+Patch:      at-3.1.14-usePOSIXtimers.patch
+Patch:      at-3.1.20-aborted-jobs.patch
+Patch:      at-3.1.18-noabort.patch
+Patch:      at-3.1.16-fclose-error.patch
+Patch:      at-3.1.16-clear-nonjobs.patch
+Patch:      at-3.1.18-utc-dst.patch
+Patch:      at-3.1.20-lock-locks.patch
+Patch:      at-3.1.23-document-n.patch
+Patch:      at-3.1.20-log-jobs.patch
 
 BuildRequires: gcc
 BuildRequires: flex flex-static bison autoconf
@@ -66,39 +66,22 @@ need to be repeated at the same time every day/week, etc. you should
 use crontab instead.
 
 %prep
-%setup -q
+%autosetup -N
 cp %{SOURCE1} .
-%patch0 -p1 -b .arm
-%patch1 -p1 -b .make
-%patch2 -p1 -b .pam
-%patch4 -p1 -b .opt_V
-%patch5 -p1 -b .shell
-%patch6 -p1 -b .nit
-%patch8 -p1 -b .export
-%patch9 -p1 -b .mail
-%patch10 -p1 -b .posix
-%patch12 -p1 -b .aborted
-%patch13 -p1 -b .noabort
-%patch14 -p1 -b .fclose
-%patch15 -p1 -b .clear-nojobs
-%patch16 -p1 -b .dst
-%patch17 -p1 -b .lock-locks
-%patch18 -p1 -b .document-n
-%patch19 -p1 -b .log-jobs
+%autopatch -p1
 
 %build
-# patch9 touches configure.in
+# at-3.1.14-usePOSIXtimers.patch touches configure.in
 autoconf
 # uselles files
 rm -f lex.yy.* y.tab.*
+
 %configure --with-atspool=%{_localstatedir}/spool/at/spool \
     --with-jobdir=%{_localstatedir}/spool/at \
     --with-daemon_username=root  \
     --with-daemon_groupname=root \
     --with-selinux \
-%if %{with pam}
-	--with-pam
-%endif
+    %{?with_pam:--with-pam}
 
 make