Build - use built-in rtmidi by default on Linux

CMakeLists.txt

@@ -44,12 +44,15 @@ set(sp_midi_sources
 if(MSVC)
     list(APPEND sp_midi_sources ${PROJECT_SOURCE_DIR}/external_libs/rtmidi/RtMidi.cpp)
     add_definitions(-D__WINDOWS_MM__)
-endif(MSVC)
-
-if(APPLE)
+elseif(APPLE)
     list(APPEND sp_midi_sources ${PROJECT_SOURCE_DIR}/external_libs/rtmidi/RtMidi.cpp)
     add_definitions(-D__MACOSX_CORE__)
-endif(APPLE)
+elseif(UNIX)
+    if(NOT USE_SYSTEM_RTMIDI)
+        list(APPEND sp_midi_sources ${PROJECT_SOURCE_DIR}/external_libs/rtmidi/RtMidi.cpp)
+        add_definitions(-D__LINUX_ALSA__)
+    endif(NOT USE_SYSTEM_RTMIDI)
+endif(MSVC)
 
 # sp_midi_sources
 add_library(libsp_midi SHARED ${sp_midi_sources})
@@ -78,6 +81,9 @@ elseif(APPLE)
 elseif(UNIX)
     add_definitions(-DLINUX=1 -DNDEBUG=1)
     include_directories(${ERLANG_INCLUDE_PATH})
-    target_link_libraries(libsp_midi pthread ${ALSA_LIBRARY} dl rtmidi)
+    target_link_libraries(libsp_midi pthread ${ALSA_LIBRARY} dl)
+    if(USE_SYSTEM_RTMIDI)
+        target_link_libraries(libsp_midi rtmidi)
+    endif(USE_SYSTEM_RTMIDI)
 endif(MSVC)