rf: build srsran_rf as static library

For Ubuntu 18.04: Linking the static srsran_rf to libuhd
also requires to link Boost's "system" library.

Newer systems do not require this special handling.

CMakeLists.txt

@@ -268,6 +268,9 @@ endif(BUILD_STATIC)
 set(BOOST_REQUIRED_COMPONENTS
   program_options
 )
+if(UHD_FOUND) # Ubuntu 18.04 requires component 'system' to link UHD
+  list(APPEND BOOST_REQUIRED_COMPONENTS "system")
+endif(UHD_FOUND)
 if(UNIX AND EXISTS "/usr/lib64")
   list(APPEND BOOST_LIBRARYDIR "/usr/lib64") #fedora 64-bit fix
 endif(UNIX AND EXISTS "/usr/lib64")

lib/src/phy/rf/CMakeLists.txt

@@ -59,12 +59,12 @@ if(RF_FOUND)
     list(APPEND SOURCES_RF rf_zmq_imp.c rf_zmq_imp_tx.c rf_zmq_imp_rx.c)
   endif (ZEROMQ_FOUND)
 
-  add_library(srsran_rf SHARED ${SOURCES_RF})
+  add_library(srsran_rf STATIC ${SOURCES_RF})
   target_link_libraries(srsran_rf srsran_rf_utils srsran_phy)
   set_target_properties(srsran_rf PROPERTIES VERSION ${SRSRAN_VERSION_STRING} SOVERSION ${SRSRAN_SOVERSION})
   
   if (UHD_FOUND)
-    target_link_libraries(srsran_rf ${UHD_LIBRARIES})
+    target_link_libraries(srsran_rf ${UHD_LIBRARIES} ${Boost_LIBRARIES}) # Ubuntu 18.04 requires 'system' from Boost_LIBRARIES
   endif (UHD_FOUND)
 
   if (BLADERF_FOUND)