ueventd: convert mkdir_recursive() to std::string

Bug: 36250207

Test: Boot bullhead
Test: Boot sailfish, observe no boot time regression
Test: init unit tests

Change-Id: I5a2ac369d846e044230b709fd07eb21ad12d47bb
diff --git a/init/util.h b/init/util.h
index 38a7bdb..0bb9cdf 100644
--- a/init/util.h
+++ b/init/util.h
@@ -60,7 +60,7 @@
 
 unsigned int decode_uid(const char *s);
 
-int mkdir_recursive(const char *pathname, mode_t mode);
+int mkdir_recursive(const std::string& pathname, mode_t mode);
 int wait_for_file(const char *filename, std::chrono::nanoseconds timeout);
 void import_kernel_cmdline(bool in_qemu,
                            const std::function<void(const std::string&, const std::string&, bool)>&);