Refactor libfastboot

This change creates a nice and clean API for issuing
fastboot commands without using the fastboot tool itself.

Test: fastboot tool itself (now using libfastboot2)
on sailfish, walleye, and other devices.
Test: flash bootloader bootloader.img
Test: flash radio radio.img
Test: -w update img.zip
Test: Manually getvar and reboot commands.

Bug: 111126621
Change-Id: I0022536b204ce0c5ad8329367fd522fa3c57877d
diff --git a/fastboot/util.h b/fastboot/util.h
new file mode 100644
index 0000000..9033f93
--- /dev/null
+++ b/fastboot/util.h
@@ -0,0 +1,19 @@
+#pragma once
+
+#include <inttypes.h>
+#include <stdlib.h>
+
+#include <string>
+
+#include <bootimg.h>
+
+/* util stuff */
+double now();
+char* xstrdup(const char*);
+void set_verbose();
+
+// These printf-like functions are implemented in terms of vsnprintf, so they
+// use the same attribute for compile-time format string checking.
+void die(const char* fmt, ...) __attribute__((__noreturn__))
+__attribute__((__format__(__printf__, 1, 2)));
+void verbose(const char* fmt, ...) __attribute__((__format__(__printf__, 1, 2)));