Avoid sendmail build dependency

sudo should be compatible with any MTA, any of which in Fedora provide
/usr/sbin/sendmail, and is used at build time only to determine its
location.  Instead of generalizing the build requirement (e.g. for RHEL
10 which includes only postfix), we can just tell sudo its location
during configure, in which case it is not needed at all to build.

However, doing so uncovered that systemd's presence was being relied
upon without being specified.  This too can be avoided by using the
macros to define the proper tmpfiles location during configure.

sudo.spec

@@ -26,7 +26,7 @@ BuildRequires: bison
 BuildRequires: libtool
 BuildRequires: audit-libs-devel libcap-devel
 BuildRequires: libselinux-devel
-BuildRequires: sendmail
+BuildRequires: systemd-rpm-macros
 BuildRequires: gettext
 BuildRequires: zlib-devel
 
@@ -89,6 +89,7 @@ export CFLAGS="$RPM_OPT_FLAGS $F_PIE" LDFLAGS="-pie -Wl,-z,relro -Wl,-z,now"
         --sbindir=%{_sbindir} \
         --libdir=%{_libdir} \
         --docdir=%{_pkgdocdir} \
+        --enable-tmpfiles.d=%{_tmpfilesdir} \
         --enable-openssl \
         --disable-root-mailer \
         --disable-intercept \
@@ -102,6 +103,7 @@ export CFLAGS="$RPM_OPT_FLAGS $F_PIE" LDFLAGS="-pie -Wl,-z,relro -Wl,-z,now"
         --with-tty-tickets \
         --with-ldap \
         --with-selinux \
+        --with-sendmail=/usr/sbin/sendmail \
         --with-passprompt="[sudo] password for %p: " \
         --enable-python \
         --enable-zlib=system \