scripts/specialize-patch: treat "#if 0" and "#if 0 && ..." as constant-false

Partial evaluation can yield guards like "+#if 0 && ...". These are false
but bypassed the filter that only matched exact "+#if 0"/"+#elif 0".
Tighten the regex to match the original spacing and catch both forms.

This is the minimal change addressing the bug observed in logs such as:

  (c) +#if 0 && !(1 && defined(FC_PORTSPEED_256GBIT)) ...
  (g2) ... output = 1   <-- wrong

After this change such guards are dropped correctly (output = 0).

scripts/specialize-patch

@@ -553,7 +553,7 @@ function process_preprocessor_statement(evaluated, condition) {
       if (debug)
         printf "/* debug specialize-patch: (g1b) %s: decision[%d] = %s */\n", \
           evaluated, i, decision[i]
-      output = output && decision[i] != "+#if 0" && decision[i] != "+#elif 0"
+      output = output && decision[i] !~ "^+#(if|elif) 0($| &&)"
     }
     if (output)
       any_section_output[if_nesting_level] = 1