waf: use ap_library tool

That way we avoid recompiling source files that don't depend on vehicles.
Change notes:
- UTILITY_SOURCE_EXTS: moved to ap_library
- Task generators indexes: ap_library handles that now and in a better way
- Use of AP_STLIB_FEATURES: it doesn't make sense anymore, since the stlib
  taskgen has empty source list
- Flags and defines: passed down to ap_library through AP_LIBRARIES_OBJECTS_KW
- Set use='mavlink' in AP_LIBRARIES_OBJECTS_KW instead of calls to
  bld.ap_stlib().

APMrover2/wscript

@@ -21,7 +21,6 @@ def build(bld):
             'AP_ServoRelayEvents',
             'PID',
         ],
-        use='mavlink',
     )
 
     bld.ap_program(

AntennaTracker/wscript

@@ -9,7 +9,6 @@ def build(bld):
         ap_libraries=bld.ap_common_vehicle_libraries() + [
             'AC_PID',
         ],
-        use='mavlink',
     )
 
     bld.ap_program(

ArduCopter/wscript

@@ -30,7 +30,6 @@ def build(bld):
             'AP_ServoRelayEvents',
             'AP_Avoidance',
         ],
-        use='mavlink',
     )
 
     frames = (

ArduPlane/wscript

@@ -31,7 +31,6 @@ def build(bld):
             'AC_Fence',
             'AC_Avoidance'
         ],
-        use='mavlink',
     )
 
     bld.ap_program(

Tools/Replay/wscript

@@ -15,7 +15,6 @@ def build(bld):
         ap_libraries=bld.ap_common_vehicle_libraries() + [
             'AP_InertialNav',
         ],
-        use='mavlink',
     )
 
     bld.ap_program(

Tools/ardupilotwaf/ardupilotwaf.py

@@ -15,8 +15,6 @@ SOURCE_EXTS = [
     '*.cpp',
 ]
 
-UTILITY_SOURCE_EXTS = [ 'utility/' + glob for glob in SOURCE_EXTS ]
-
 COMMON_VEHICLE_DEPENDENT_LIBRARIES = [
     'AP_AccelCal',
     'AP_ADC',
@@ -147,17 +145,6 @@ def ap_example(bld, **kw):
     kw['program_groups'] = 'examples'
     ap_program(bld, use_legacy_defines=False, **kw)
 
-# NOTE: Code in libraries/ is compiled multiple times. So ensure each
-# compilation is independent by providing different index for each.
-# The need for this should disappear when libraries change to be
-# independent of vehicle type.
-LAST_IDX = 0
-
-def _get_next_idx():
-    global LAST_IDX
-    LAST_IDX += 1
-    return LAST_IDX
-
 def unique_list(items):
     '''remove duplicate elements from a list while maintaining ordering'''
     return list(OrderedDict.fromkeys(items))
@@ -171,22 +158,13 @@ def ap_stlib(bld, **kw):
     if 'ap_libraries' not in kw:
         bld.fatal('Missing ap_libraries for ap_stlib')
 
-    sources = []
-    libraries = unique_list(kw['ap_libraries'] + bld.env.AP_LIBRARIES)
+    kw['ap_libraries'] = unique_list(kw['ap_libraries'] + bld.env.AP_LIBRARIES)
+    for l in kw['ap_libraries']:
+        bld.ap_library(l, kw['ap_vehicle'])
 
-    for lib_name in libraries:
-        lib_node = bld.srcnode.find_dir('libraries/' + lib_name)
-        if lib_node is None:
-            bld.fatal('Could not find library ' + lib_name)
-        lib_sources = lib_node.ant_glob(SOURCE_EXTS + UTILITY_SOURCE_EXTS)
-        sources.extend(lib_sources)
-
-    kw['cxxflags'] = kw.get('cxxflags', []) + ['-include', 'ap_config.h']
-    kw['features'] = kw.get('features', []) + bld.env.AP_STLIB_FEATURES
-    kw['source'] = sources
+    kw['features'] = kw.get('features', []) + ['cxx', 'cxxstlib']
     kw['target'] = kw['name']
-    kw['defines'] = get_legacy_defines(kw['ap_vehicle'])
-    kw['idx'] = _get_next_idx()
+    kw['source'] = []
 
     bld.stlib(**kw)
 
@@ -395,10 +373,5 @@ my board".
 
 
 def build(bld):
-    global LAST_IDX
-    # FIXME: This is done to prevent same task generators being created with
-    # different idx when build() is called multiple times (e.g. waf bin tests).
-    # Ideally, task generators should be created just once.
-    LAST_IDX = 0
     bld.add_pre_fun(_process_build_command)
     bld.add_pre_fun(_select_programs_from_group)

wscript

@@ -152,6 +152,8 @@ def configure(cfg):
         cfg.msg('Using static linking', 'yes', color='YELLOW')
         cfg.env.STATIC_LINKING = True
 
+    cfg.load('ap_library')
+
     cfg.msg('Setting board to', cfg.options.board)
     cfg.get_board().configure(cfg)
 
@@ -272,7 +274,6 @@ def _build_common_taskgens(bld):
         name='ap',
         ap_vehicle='UNKNOWN',
         ap_libraries=bld.ap_get_all_libraries(),
-        use='mavlink',
     )
 
     if bld.env.HAS_GTEST:
@@ -344,6 +345,11 @@ def build(bld):
 
     bld.load('ardupilotwaf')
 
+    bld.env.AP_LIBRARIES_OBJECTS_KW.update(
+        use='mavlink',
+        cxxflags=['-include', 'ap_config.h'],
+    )
+
     _build_cmd_tweaks(bld)
 
     if bld.env.SUBMODULE_UPDATE: