compton error message using -lrt on openbsd 5.5

└── ~/compton »sudo gmake CC=egcc
egcc -std=c99 -DCONFIG_XINERAMA -DCONFIG_LIBCONFIG  -DCONFIG_REGEX_PCRE -DCONFIG_REGEX_PCRE_JIT -DCONFIG_VSYNC_DRM -DCONFIG_VSYNC_OPENGL -DCONFIG_VSYNC_OPENGL_GLSL -DCONFIG_VSYNC_OPENGL_FBO -DCONFIG_VSYNC_OPENGL_VBO -DCONFIG_DBUS -DCONFIG_C2 -DCOMPTON_VERSION="\"git-v0.1_beta2-19-g44faf1a-2014-02-26\""  -DNDEBUG -O2 -D_FORTIFY_SOURCE=2 -Wall  -I/usr/local/include -I/usr/X11R6/include -I/usr/include/dev/pci/drm -I/usr/X11R6/include -I/usr/local/include -I/usr/local/include/dbus-1.0 -I/usr/local/lib/dbus-1.0/include -c src/compton.c
In file included from src/compton.h:10:0,
                 from src/compton.c:11:
src/common.h: In function 'print_timestamp':
src/common.h:1332:3: warning: format '%ld' expects argument of type 'long int', but argument 2 has type 'time_t' [-Wformat=]
   printf("[ %5ld.%02ld ] ", diff.tv_sec, diff.tv_usec / 10000);
   ^
In file included from src/compton.c:11:0:
src/compton.h: In function 'set_tgt_clip':
src/compton.h:687:3: warning: enumeration value 'NUM_BKEND' not handled in switch [-Wswitch]
   switch (ps->o.backend) {
   ^
src/compton.c: In function 'win_paint_win':
src/compton.c:1645:5: warning: enumeration value 'NUM_BKEND' not handled in switch [-Wswitch]
     switch (ps->o.backend) {
     ^
src/compton.c: In function 'init_filters':
src/compton.c:6247:5: warning: enumeration value 'NUM_BKEND' not handled in switch [-Wswitch]
     switch (ps->o.backend) {
     ^
src/compton.c: At top level:
src/compton.c:2571:1: warning: 'win_upd_run' defined but not used [-Wunused-function]
 win_upd_run(session_t *ps, win *w, win_upd_t *pupd) {
 ^
egcc -std=c99 -DCONFIG_XINERAMA -DCONFIG_LIBCONFIG  -DCONFIG_REGEX_PCRE -DCONFIG_REGEX_PCRE_JIT -DCONFIG_VSYNC_DRM -DCONFIG_VSYNC_OPENGL -DCONFIG_VSYNC_OPENGL_GLSL -DCONFIG_VSYNC_OPENGL_FBO -DCONFIG_VSYNC_OPENGL_VBO -DCONFIG_DBUS -DCONFIG_C2 -DCOMPTON_VERSION="\"git-v0.1_beta2-19-g44faf1a-2014-02-26\""  -DNDEBUG -O2 -D_FORTIFY_SOURCE=2 -Wall  -I/usr/local/include -I/usr/X11R6/include -I/usr/include/dev/pci/drm -I/usr/X11R6/include -I/usr/local/include -I/usr/local/include/dbus-1.0 -I/usr/local/lib/dbus-1.0/include -c src/opengl.c
In file included from src/opengl.h:11:0,
                 from src/opengl.c:11:
src/common.h: In function 'print_timestamp':
src/common.h:1332:3: warning: format '%ld' expects argument of type 'long int', but argument 2 has type 'time_t' [-Wformat=]
   printf("[ %5ld.%02ld ] ", diff.tv_sec, diff.tv_usec / 10000);
   ^
src/opengl.c: At top level:
src/opengl.c:1426:1: warning: 'glx_render_color' defined but not used [-Wunused-function]
 glx_render_color(session_t *ps, int dx, int dy, int width, int height, int z,
 ^
src/opengl.c:1464:1: warning: 'glx_render_dots' defined but not used [-Wunused-function]
 glx_render_dots(session_t *ps, int dx, int dy, int width, int height, int z,
 ^
egcc -std=c99 -DCONFIG_XINERAMA -DCONFIG_LIBCONFIG  -DCONFIG_REGEX_PCRE -DCONFIG_REGEX_PCRE_JIT -DCONFIG_VSYNC_DRM -DCONFIG_VSYNC_OPENGL -DCONFIG_VSYNC_OPENGL_GLSL -DCONFIG_VSYNC_OPENGL_FBO -DCONFIG_VSYNC_OPENGL_VBO -DCONFIG_DBUS -DCONFIG_C2 -DCOMPTON_VERSION="\"git-v0.1_beta2-19-g44faf1a-2014-02-26\""  -DNDEBUG -O2 -D_FORTIFY_SOURCE=2 -Wall  -I/usr/local/include -I/usr/X11R6/include -I/usr/include/dev/pci/drm -I/usr/X11R6/include -I/usr/local/include -I/usr/local/include/dbus-1.0 -I/usr/local/lib/dbus-1.0/include -c src/dbus.c
In file included from src/dbus.h:11:0,
                 from src/dbus.c:11:
src/common.h: In function 'print_timestamp':
src/common.h:1332:3: warning: format '%ld' expects argument of type 'long int', but argument 2 has type 'time_t' [-Wformat=]
   printf("[ %5ld.%02ld ] ", diff.tv_sec, diff.tv_usec / 10000);
   ^
egcc -std=c99 -DCONFIG_XINERAMA -DCONFIG_LIBCONFIG  -DCONFIG_REGEX_PCRE -DCONFIG_REGEX_PCRE_JIT -DCONFIG_VSYNC_DRM -DCONFIG_VSYNC_OPENGL -DCONFIG_VSYNC_OPENGL_GLSL -DCONFIG_VSYNC_OPENGL_FBO -DCONFIG_VSYNC_OPENGL_VBO -DCONFIG_DBUS -DCONFIG_C2 -DCOMPTON_VERSION="\"git-v0.1_beta2-19-g44faf1a-2014-02-26\""  -DNDEBUG -O2 -D_FORTIFY_SOURCE=2 -Wall  -I/usr/local/include -I/usr/X11R6/include -I/usr/include/dev/pci/drm -I/usr/X11R6/include -I/usr/local/include -I/usr/local/include/dbus-1.0 -I/usr/local/lib/dbus-1.0/include -c src/c2.c
In file included from src/c2.h:11:0,
                 from src/c2.c:11:
src/common.h: In function 'print_timestamp':
src/common.h:1332:3: warning: format '%ld' expects argument of type 'long int', but argument 2 has type 'time_t' [-Wformat=]
   printf("[ %5ld.%02ld ] ", diff.tv_sec, diff.tv_usec / 10000);
   ^
egcc -std=c99 -DCONFIG_XINERAMA -DCONFIG_LIBCONFIG  -DCONFIG_REGEX_PCRE -DCONFIG_REGEX_PCRE_JIT -DCONFIG_VSYNC_DRM -DCONFIG_VSYNC_OPENGL -DCONFIG_VSYNC_OPENGL_GLSL -DCONFIG_VSYNC_OPENGL_FBO -DCONFIG_VSYNC_OPENGL_VBO -DCONFIG_DBUS -DCONFIG_C2 -DCOMPTON_VERSION="\"git-v0.1_beta2-19-g44faf1a-2014-02-26\""  -Wl,-O1 -Wl,--as-needed -DNDEBUG -O2 -D_FORTIFY_SOURCE=2 -Wall -o compton compton.o opengl.o dbus.o c2.o -lGL -lm -lrt -L/usr/local/lib -Wl,-R/usr/local/lib -lpcre -L/usr/X11R6/lib -L/usr/local/lib -lXcomposite -lXdamage -lXfixes -lXrender -lX11 -lXext -lXrandr -lXinerama -lconfig -ldbus-1
/usr/bin/ld: cannot find -lrt
collect2: error: ld returned 1 exit status
Makefile:118: recipe for target 'compton' failed
gmake: *** [compton] Error 1