cmake: qurt fix to build shared lib, not executable

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

cmake/qurt/configs/config-qurt-hil.cmake

@@ -6,6 +6,7 @@ function(px4_set_config_modules out_module_list)
 		drivers/led
 		drivers/rgbled
 		modules/sensors
+		modules/uORB
 
 	#	drivers/blinkm
 	#	drivers/ms5611

src/firmware/qurt/CMakeLists.txt

@@ -25,7 +25,7 @@ px4_qurt_generate_builtin_commands(
 set(CMAKE_SHARED_LIBRARY_LINK_C_FLAGS "")
 set(CMAKE_SHARED_LIBRARY_LINK_CXX_FLAGS "")
 
-add_executable(mainapp builtin_commands.cpp)
+add_library(mainapp builtin_commands.cpp)
 target_link_libraries(mainapp
 	-Wl,--whole-archive
 	${module_list}