Add cmake options that enable/disable grcc compilation

To disable compilation of both grgsm_livemon and grgsm_livemon_headless
execute

  cmake -DENABLE_GRCC=OFF ..

To disable only one execute

  cmake -DENABLE_GRGSM_LIVEMON=OFF ..
  cmake -DENABLE_GRGSM_LIVEMON_HEADLESS=OFF ..
diff --git a/apps/CMakeLists.txt b/apps/CMakeLists.txt
index 5b12076..fe52119 100644
--- a/apps/CMakeLists.txt
+++ b/apps/CMakeLists.txt
@@ -73,10 +73,22 @@
     add_custom_target(${_target} ALL DEPENDS ${ARGN})
 endfunction(GR_UNIQUE_TARGET)
 
+set(grgsm_flowgraphs "")
+OPTION(ENABLE_GRCC "Compile the flowgraphs with grcc" ON)
+OPTION(ENABLE_GRGSM_LIVEMON "Compile grgsm_livemon" ON)
+OPTION(ENABLE_GRGSM_LIVEMON_HEADLESS "Compile grgsm_livemon_headless" ON)
+
+if(ENABLE_GRCC AND ENABLE_GRGSM_LIVEMON)
+    list (APPEND grgsm_flowgraphs ${CMAKE_CURRENT_BINARY_DIR}/grgsm_livemon)
+endif(ENABLE_GRCC AND ENABLE_GRGSM_LIVEMON)
+
+if(ENABLE_GRCC AND ENABLE_GRGSM_LIVEMON_HEADLESS)
+    list (APPEND grgsm_flowgraphs ${CMAKE_CURRENT_BINARY_DIR}/grgsm_livemon_headless)
+endif(ENABLE_GRCC AND ENABLE_GRGSM_LIVEMON_HEADLESS)
+
 GR_PYTHON_INSTALL(
     PROGRAMS
-    ${CMAKE_CURRENT_BINARY_DIR}/grgsm_livemon
-    ${CMAKE_CURRENT_BINARY_DIR}/grgsm_livemon_headless
+    ${grgsm_flowgraphs}
     grgsm_scanner
     grgsm_decode
     grgsm_trx