Provide better control of sharing the defaults.

When using the set builder and nesting builds prpvide the nested
set builder and build objects with copies of the master defaults.
Python's variable sharing was sharing a single set of defaults
across all build sets and this resulted in popluted configurations.

source-builder/sb/defaults.py

@@ -216,16 +216,6 @@ FFLAGS="${FFLAGS:-%optflags}" ; export FFLAGS ;
 class command_line:
     """Process the command line in a common way for all Tool Builder commands."""
 
-    _defaults = { 'params'   : [],
-                  'warn-all' : '0',
-                  'quiet'    : '0',
-                  'force'    : '0',
-                  'trace'    : '0',
-                  'dry-run'  : '0',
-                  'no-clean' : '0',
-                  'no-smp'   : '0',
-                  'rebuild'  : '0' }
-
     #
     # The define and if it is a path and needs conversion.
     #
@@ -292,12 +282,22 @@ class command_line:
         if len(self.command_path) == 0:
             self.command_path = '.'
         self.command_name = path.basename(argv[0])
+        self.argv = argv
         self.args = argv[1:]
         self.optargs = optargs
         self.defaults = {}
         for to in command_line._long_true_opts:
             self.defaults[command_line._long_true_opts[to]] = ('none', 'none', '0')
         self.defaults['_sbdir'] = ('dir', 'required', path.shell(self.command_path))
+        self.opts = { 'params'   : [],
+                      'warn-all' : '0',
+                      'quiet'    : '0',
+                      'force'    : '0',
+                      'trace'    : '0',
+                      'dry-run'  : '0',
+                      'no-clean' : '0',
+                      'no-smp'   : '0',
+                      'rebuild'  : '0' }
         self._process()
 
     def __str__(self):
@@ -339,7 +339,6 @@ class command_line:
                     return lo, long_opts[lo], True, arg
             return None, None, None, arg
 
-        self.opts = command_line._defaults
         i = 0
         while i < len(self.args):
             a = self.args[i]
@@ -502,7 +501,7 @@ class command_line:
             if not configbase.endswith('.cfg'):
                 configbase = configbase + '.cfg'
             if len(configdir) == 0:
-                configdir = self.expand(defaults['_configdir'][2], defaults)
+                configdir = self.expand(self.defaults['_configdir'][2], self.defaults)
             configs = []
             for cp in configdir.split(':'):
                 hostconfigdir = path.host(cp)
@@ -540,7 +539,8 @@ def load(args, optargs = None):
     line merging in any command line overrides. Finally post process the
     command line.
     """
-    d = defaults
+    import copy
+    d = copy.deepcopy(defaults)
     overrides = None
     if os.name == 'nt':
         import windows