fix(config): parse zero-prefixed decimal values as base 10

The defconfig grammar accepts signed decimal digit sequences, but
int(raw, 0) rejects nonzero decimal values with leading zeroes, such
as 08, 010 and -08. Select base 16 only for the existing 0x form and
base 10 otherwise, preserving signed hexadecimal values.

Add 16 numeric regression cases to the build driver's existing
self-test.

scripts/check-unixnu.py

@@ -50,6 +50,13 @@ def der(tag, body):
 def main():
     config = parse_config('# c\nCONFIG_A=y\nCONFIG_B=n\n# CONFIG_C is not set\nCONFIG_D="x y"\nCONFIG_E=0x10\n')
     expect(config == {'A': True, 'B': False, 'C': False, 'D': 'x y', 'E': 16}, 'defconfig values')
+    for raw, value in (
+        ('0', 0), ('-0', 0), ('00', 0), ('-00', 0),
+        ('8', 8), ('-8', -8), ('08', 8), ('-08', -8),
+        ('010', 10), ('-010', -10), ('00042', 42), ('-00042', -42),
+        ('0x10', 16), ('-0x10', -16), ('0x00FF', 255), ('-0x00FF', -255),
+    ):
+        expect(parse_config(f'CONFIG_NUMBER={raw}\n') == {'NUMBER': value}, f'defconfig number: {raw}')
     try:
         parse_config('CONFIG_A=maybe\n')
         expect(False, 'bad defconfig value accepted')

scripts/unixnu/config.py

@@ -51,7 +51,7 @@ def parse_config(text):
         elif raw.startswith('"') and raw.endswith('"') and len(raw) >= 2:
             values[name] = raw[1:-1]
         elif re.fullmatch(r'-?(0x[0-9a-fA-F]+|\d+)', raw):
-            values[name] = int(raw, 0)
+            values[name] = int(raw, 16 if raw.lstrip('-').startswith('0x') else 10)
         else:
             raise Error(f'defconfig line {number}: value must be y, n, a number or a quoted string: {line}')
     return values