GNU Radio 3.8 support

https://wiki.gnuradio.org/index.php/GNU_Radio_3.8_OOT_Module_Porting_Guide

Change-Id: I23dd638c8c48ed0a4b50559ce33fbd5e60b7dcbc
diff --git a/swig/CMakeLists.txt b/swig/CMakeLists.txt
index 4766220..5f1e020 100644
--- a/swig/CMakeLists.txt
+++ b/swig/CMakeLists.txt
@@ -1,6 +1,7 @@
 # Copyright 2011 Free Software Foundation, Inc.
 #
-# This file is part of GNU Radio
+# This file was generated by gr_modtool, a tool from the GNU Radio framework
+# This file is a part of gr-gsm
 #
 # GNU Radio is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -18,31 +19,32 @@
 # Boston, MA 02110-1301, USA.
 
 ########################################################################
+# Check if there is C++ code at all
+########################################################################
+if(NOT grgsm_sources)
+    MESSAGE(STATUS "No C++ sources... skipping swig/")
+    return()
+endif(NOT grgsm_sources)
+
+########################################################################
 # Include swig generation macros
 ########################################################################
 find_package(SWIG)
-find_package(PythonLibs 2)
+find_package(PythonLibs)
 if(NOT SWIG_FOUND OR NOT PYTHONLIBS_FOUND)
     return()
 endif()
 include(GrSwig)
 include(GrPython)
 
-IF(${CMAKE_SYSTEM_NAME} MATCHES "Darwin")
-  # Mac OS X specific code
-  # Without this flag it does not find some of the libraries
-  SET(CMAKE_MODULE_LINKER_FLAGS "-undefined dynamic_lookup")
-ENDIF(${CMAKE_SYSTEM_NAME} MATCHES "Darwin")
-
 ########################################################################
 # Setup swig generation
 ########################################################################
-foreach(incdir ${GNURADIO_RUNTIME_INCLUDE_DIRS})
-    list(APPEND GR_SWIG_INCLUDE_DIRS ${incdir}/gnuradio/swig)
-endforeach(incdir)
-list(APPEND GR_SWIG_INCLUDE_DIRS ${FFTW3F_INCLUDE_DIRS})
+set(GR_SWIG_INCLUDE_DIRS $<TARGET_PROPERTY:gnuradio::runtime_swig,INTERFACE_INCLUDE_DIRECTORIES>)
+set(GR_SWIG_TARGET_DEPS gnuradio::runtime_swig)
 
 set(GR_SWIG_LIBRARIES grgsm)
+
 set(GR_SWIG_DOC_FILE ${CMAKE_CURRENT_BINARY_DIR}/grgsm_swig_doc.i)
 set(GR_SWIG_DOC_DIRS ${CMAKE_CURRENT_SOURCE_DIR}/../include)
 
@@ -59,7 +61,6 @@
 install(
     FILES
     grgsm_swig.i
-    constants.i
     ${CMAKE_CURRENT_BINARY_DIR}/grgsm_swig_doc.i
     DESTINATION ${GR_INCLUDE_DIR}/grgsm/swig
 )