Introduce global_flags

Set this to True to export LDFLAGS and similar as global variables, as opposed
to being local just for the configure step (the default). No packages are
affected by this until you set 'global_flags: true'.

Author: certik

base/autotools_package.py

@@ -19,6 +19,7 @@ def configure(ctx, stage_args):
           set_env_flags: true # default
           env_flags_append: {'LDFLAGS', '-Wl,-rpath=${ARTIFACT}/lib'} # only meaningful if set_env_flags: true
           configure_path: . # default
+          global_flags: false # default
 
     If set_env_flags is set, CPPFLAGS and LDFLAGS will be set, as appropriate for the
     platform.
@@ -45,4 +46,8 @@ def configure(ctx, stage_args):
         for env_var, value in env.items():
             env_lines.append('export %s="%s"' % (env_var, ' '.join(value)))
 
-    return ['('] + env_lines + conf_lines + [')']
+    r = env_lines + conf_lines
+    if not stage_args.get('global_flags', False):
+        r = ['('] + r + [')']
+
+    return r