Launch libc initialization after hardware setup

This sometimes helps libraries that setups hardware in class
constructor to work properly (in other words allows C++ global
constructors to run after hardware initialization).

See also arduino#169

Author: cmaglie

cores/arduino/cortex_handlers.c

@@ -134,7 +134,6 @@ __attribute__ ((section(".isr_vector"))) const DeviceVectors exception_table =
 };
 
 extern int main(void);
-extern void __libc_init_array(void);
 
 /* This is called on processor reset to initialize the device and call main() */
 void Reset_Handler(void)
@@ -156,9 +155,6 @@ void Reset_Handler(void)
       *pDest = 0;
   }
 
-  /* Initialize the C library */
-  __libc_init_array();
-
   SystemInit();
 
   main();

cores/arduino/main.cpp

@@ -24,13 +24,18 @@
 void initVariant() __attribute__((weak));
 void initVariant() { }
 
+// Initialize C library
+extern "C" void __libc_init_array(void);
+
 /*
  * \brief Main entry point of Arduino application
  */
 int main( void )
 {
   init();
 
+  __libc_init_array();
+
   initVariant();
 
   delay(1);