waf: add post build callbacks in separate function

That makes it easier see what callbacks are or not being added and the order
they are executed. While at it, don't add build summary callback when in a
check command.

wscript

@@ -217,10 +217,9 @@ def _build_cmd_tweaks(bld):
         bld.cmd = 'check'
 
     if bld.cmd == 'check':
-        bld.options.clear_failed_tests = True
         if not bld.env.HAS_GTEST:
             bld.fatal('check: gtest library is required')
-        bld.add_post_fun(ardupilotwaf.test_summary)
+        bld.options.clear_failed_tests = True
 
 def _build_dynamic_sources(bld):
     bld(
@@ -307,6 +306,14 @@ def _write_version_header(tsk):
     bld = tsk.generator.bld
     return bld.write_version_header(tsk.outputs[0].abspath())
 
+def _build_post_funs(bld):
+    if bld.cmd == 'check':
+        bld.add_post_fun(ardupilotwaf.test_summary)
+    else:
+        bld.build_summary_post_fun()
+
+    if bld.env.SUBMODULE_UPDATE:
+        bld.git_submodule_post_fun()
 
 def build(bld):
     config_hash = Utils.h_file(bld.bldnode.make_node('ap_config.h').abspath())
@@ -341,9 +348,7 @@ def build(bld):
         group='dynamic_sources',
     )
 
-    bld.load('build_summary')
-    if bld.env.SUBMODULE_UPDATE:
-        bld.git_submodule_post_fun()
+    _build_post_funs(bld)
 
 ardupilotwaf.build_command('check',
     program_group_list='all',