Modify extract_configs.py to deal with _u(X) macros (#222)

diff --git a/tools/extract_configs.py b/tools/extract_configs.py
index 0c8a881..e45ae7c 100755
--- a/tools/extract_configs.py
+++ b/tools/extract_configs.py
@@ -171,6 +171,11 @@
                             m = re.match(r'^((0x)?\d+)u$', value.lower())
                             if m:
                                 value = m.group(1)
+                            else:
+                                # discard any '_u(X)' macro
+                                m = re.match(r'^_u\(((0x)?\d+)\)$', value.lower())
+                                if m:
+                                    value = m.group(1)
                             if name not in all_defines:
                                 all_defines[name] = dict()
                             if value not in all_defines[name]: