Make flag optional if libbluetooth is installed

host/ubertooth-tools/src/CMakeLists.txt

@@ -23,6 +23,7 @@
 
 find_package(BTBB REQUIRED)
 find_package(PCAP)
+find_package(BLUETOOTH)
 
 if(MSVC)
 	include_directories(../getopt)
@@ -54,13 +55,16 @@ endif()
 
 LIST(APPEND TOOLS ubertooth-rx ubertooth-dump ubertooth-util ubertooth-btle)
 
-if(USE_BLUEZ)
-	find_package(BLUETOOTH REQUIRED)
-	if ( ${LIBBLUETOOTH_FOUND} )
-		LIST(APPEND TOOLS ubertooth-follow ubertooth-scan)
-		include_directories(${LIBBLUETOOTH_INCLUDE_DIR})
-		LIST(APPEND TOOLS_LINK_LIBS ${LIBBLUETOOTH_LIBRARIES})
-	endif()
+if( USE_BLUEZ AND NOT ${LIBBLUETOOTH_FOUND} )
+	message( FATAL_ERROR
+		"Cannot find libbluetooth, which is required for USE_BLUEZ")
+
+endif()
+
+if ( ${LIBBLUETOOTH_FOUND} )
+	LIST(APPEND TOOLS ubertooth-follow ubertooth-scan)
+	include_directories(${LIBBLUETOOTH_INCLUDE_DIR})
+	LIST(APPEND TOOLS_LINK_LIBS ${LIBBLUETOOTH_LIBRARIES})
 endif()
 
 foreach(tool ${TOOLS})