Update cmake modules from Gnuradio to fix parallel build bug

cmake/Modules/GrPython.cmake

@@ -76,10 +76,11 @@ macro(GR_PYTHON_CHECK_MODULE desc mod cmd have)
     execute_process(
         COMMAND ${PYTHON_EXECUTABLE} -c "
 #########################################
-try: import ${mod}
-except: exit(-1)
-try: assert ${cmd}
-except: exit(-1)
+try:
+    import ${mod}
+    assert ${cmd}
+except ImportError, AssertionError: exit(-1)
+except: pass
 #########################################"
         RESULT_VARIABLE ${have}
     )
@@ -181,6 +182,10 @@ function(GR_PYTHON_INSTALL)
     ####################################################################
         file(TO_NATIVE_PATH ${PYTHON_EXECUTABLE} pyexe_native)
 
+        if (CMAKE_CROSSCOMPILING)
+           set(pyexe_native /usr/bin/env python)
+        endif()
+
         foreach(pyfile ${GR_PYTHON_INSTALL_PROGRAMS})
             get_filename_component(pyfile_name ${pyfile} NAME)
             get_filename_component(pyfile ${pyfile} ABSOLUTE)