waf: process board and project configuration before toolchain

Several boards require cross compilation. The objective of this change is to
allow to specify the target architecture in the board definition, so that the
correct toolchain is selected. The cross compilation mechanism will be
implemented in the next commits.

wscript

@@ -58,6 +58,22 @@ def configure(cfg):
     # use a different variant for each board
     cfg.setenv(cfg.env.BOARD)
 
+    cfg.msg('Setting board to', cfg.options.board)
+    cfg.env.BOARD = cfg.options.board
+    board_dict = boards.BOARDS[cfg.env.BOARD].get_merged_dict()
+
+    # Always prepend so that arguments passed in the command line get
+    # the priority.
+    for k in board_dict:
+        val = board_dict[k]
+        # Dictionaries (like 'DEFINES') are converted to lists to
+        # conform to waf conventions.
+        if isinstance(val, dict):
+            for item in val.items():
+                cfg.env.prepend_value(k, '%s=%s' % item)
+        else:
+            cfg.env.prepend_value(k, val)
+
     cfg.load('compiler_cxx compiler_c')
     cfg.load('clang_compilation_database')
     cfg.load('waf_unit_test')
@@ -76,22 +92,6 @@ def configure(cfg):
         errmsg='not found, unit tests disabled',
     )
 
-    cfg.msg('Setting board to', cfg.options.board)
-    cfg.env.BOARD = cfg.options.board
-    board_dict = boards.BOARDS[cfg.env.BOARD].get_merged_dict()
-
-    # Always prepend so that arguments passed in the command line get
-    # the priority.
-    for k in board_dict:
-        val = board_dict[k]
-        # Dictionaries (like 'DEFINES') are converted to lists to
-        # conform to waf conventions.
-        if isinstance(val, dict):
-            for item in val.items():
-                cfg.env.prepend_value(k, '%s=%s' % item)
-        else:
-            cfg.env.prepend_value(k, val)
-
     cfg.env.prepend_value('INCLUDES', [
         cfg.srcnode.abspath() + '/libraries/'
     ])