Remove stale libevent(-devel) dependency

It appears that the last user of libevent disappeared with
44e92dc8b900 ("Ticket 50669 - remove nunc-stans").

configure.ac

@@ -801,8 +801,6 @@ AM_CONDITIONAL([FREEBSD],[test "$platform" = "freebsd"])
 AM_CONDITIONAL([SPARC],[test "x$TARGET" = xSPARC])
 
 # Check for library dependencies
-PKG_CHECK_MODULES([EVENT], [libevent])
-
 if $PKG_CONFIG --exists nspr; then
     PKG_CHECK_MODULES([NSPR], [nspr])
 else

docker/389-ds-suse/Dockerfile

@@ -16,7 +16,7 @@ RUN zypper --non-interactive si --build-deps-only 389-ds && \
 
 # Install build dependencies
 # RUN zypper in -C -y autoconf automake cracklib-devel cyrus-sasl-devel db-devel doxygen gcc-c++ \
-#   gdb krb5-devel libcmocka-devel libevent-devel libtalloc-devel libtevent-devel libtool \
+#   gdb krb5-devel libcmocka-devel libtalloc-devel libtevent-devel libtool \
 #   net-snmp-devel openldap2-devel pam-devel pkgconfig python-rpm-macros "pkgconfig(icu-i18n)" \
 #   "pkgconfig(icu-uc)" "pkgconfig(libcap)" "pkgconfig(libpcre)" "pkgconfig(libsystemd)" \
 #   "pkgconfig(nspr)" "pkgconfig(nss)" rsync cargo rust rust-std acl cyrus-sasl-plain db-utils \

rpm/389-ds-base.spec.in

@@ -220,7 +220,6 @@ BuildRequires:    libtool
 BuildRequires:    doxygen
 # For tests!
 BuildRequires:    libcmocka-devel
-BuildRequires:    libevent-devel
 # For lib389 and related components.
 BuildRequires:    python%{python3_pkgversion}
 BuildRequires:    python%{python3_pkgversion}-devel
@@ -316,7 +315,6 @@ Conflicts:        svrcore
 Requires:         nss >= 3.34
 Requires:         nspr
 Requires:         openldap
-Requires:         libevent
 Requires:         systemd-libs
 # Pull in sasl
 Requires:         cyrus-sasl-lib