fixup! annotate_ifdef_directives: remove some cases of double negation

Fix our logic for removing double negation, thanks to tests added
later in the branch.

scripts/maint/annotate_ifdef_directives

@@ -55,16 +55,42 @@ def commented_line(fmt, argument, maxwidth=LINE_WIDTH):
         return result
 
 def negate(expr):
-    """Return a negated version of expr; try to avoid double-negation."""
+    """Return a negated version of expr; try to avoid double-negation.
+
+    We usually wrap expressions in parentheses and add a "!".
+    >>> negate("A && B")
+    '!(A && B)'
+
+    But if we recognize the expression as negated, we can restore it.
+    >>> negate(negate("A && B"))
+    'A && B'
+
+    The same applies for defined(FOO).
+    >>> negate("defined(FOO)")
+    '!defined(FOO)'
+    >>> negate(negate("defined(FOO)"))
+    'defined(FOO)'
+
+    Internal parentheses don't confuse us:
+    >>> negate("!(FOO) && !(BAR)")
+    '!(!(FOO) && !(BAR))'
+
+    """
     expr = expr.strip()
     # See whether we match !(...), with no intervening close-parens.
-    m = re.match(r'^!\s*\(([^\)*])\)$', expr)
+    m = re.match(r'^!\s*\(([^\)]*)\)$', expr)
     if m:
         return m.group(1)
-    # See whether we match !defined(...), with no intervening close-parens.
-    m = re.match(r'^!\s*(defined\([^\)]*\))$', expr)
+
+
+    # See whether we match !?defined(...), with no intervening close-parens.
+    m = re.match(r'^(!?)\s*(defined\([^\)]*\))$', expr)
     if m:
-        return m.group(1)
+        if m.group(1) == "!":
+            prefix = ""
+        else:
+            prefix = "!"
+        return prefix + m.group(2)
 
     return "!(%s)" % expr