lib: convey input character set to w3m

There is no need for w3m to guess from a <meta> tag; the charset is
available from PR_INTERNET_CPID. In particular, if there was a
character set conversion, <meta> is out of date (only
PR_INTERNET_CPID is current).

Always pass -I to w3m.

Author: jengelh

lib/rfbl.cpp

@@ -525,7 +525,18 @@ int feed_w3m(const void *inbuf, size_t len, const char *cset,
 	fp.reset();
 	int fout = -1;
 	auto cl2 = HX::make_scope_exit([&]() { if (fout != -1) close(fout); });
-	const char *const argv[] = {"w3m", "-O", "UTF-8", "-dump", filename.c_str(), nullptr};
+	const char *argv[8];
+	int argc = 0;
+	argv[argc++] = "w3m";
+	if (cset != nullptr) {
+		argv[argc++] = "-I";
+		argv[argc++] = cset;
+	}
+	argv[argc++] = "-O";
+	argv[argc++] = "UTF-8";
+	argv[argc++] = "-dump";
+	argv[argc++] = filename.c_str();
+	argv[argc]   = nullptr;
 	auto pid = popenfd(argv, nullptr, &fout, nullptr, const_cast<const char *const *>(environ));
 	if (pid < 0)
 		return -1;