build: install targets for f00bar binary + module plugins

Module plugins are (still) built in <build-dir>/modules.

When installing, f00bar binary is installed to <install-dir>/bin, and
the module plugins to <install-dir>/lib/f00bar.

For this to work, we now also set RPATH correctly. Since the installed
module plugins end up in a different location then when building,
different settings is required for BUILD_RPATH and INSTALL_RPATH.

CMakeLists.txt

@@ -84,4 +84,9 @@ target_compile_options(module-sdk INTERFACE ${CAIRO_CFLAGS_OTHER})
 target_include_directories(module-sdk INTERFACE ${CAIRO_INCLUDE_DIRS})
 target_link_libraries(module-sdk INTERFACE ${CMAKE_THREAD_LIBS_INIT})
 
+set_property(TARGET f00bar PROPERTY INSTALL_RPATH \$ORIGIN/../lib/f00bar)
+set_property(TARGET f00bar PROPERTY BUILD_RPATH \$ORIGIN/modules)
+
+install(TARGETS f00bar DESTINATION bin)
+
 add_subdirectory(modules)

modules/CMakeLists.txt

@@ -52,3 +52,19 @@ target_link_libraries(xkb module-sdk ${XCB_XKB_LIBRARIES})
 
 add_library(xwindow MODULE xwindow/xwindow.c xwindow/xwindow.h)
 target_link_libraries(xwindow module-sdk)
+
+install(
+  TARGETS
+  alsa
+  backlight
+  battery
+  clock
+  i3
+  label
+  mpd
+  network
+  removables
+  xkb
+  xwindow
+
+  DESTINATION lib/f00bar)

plugin.c

@@ -38,7 +38,7 @@ const struct module_info *
 plugin_load_module(const char *name)
 {
     char path[128];
-    snprintf(path, sizeof(path), "./modules/lib%s.so", name);
+    snprintf(path, sizeof(path), "lib%s.so", name);
 
     /* Have we already loaded it? */
     tll_foreach(libs, plug) {