cores/arduino/abi: squash warning

Use a global 'extern "C" { }' block to avoid warnings about variables
being initialized and declared extern.

Signed-off-by: Luca Burelli <[email protected]>

Author: pillo79

cores/arduino/abi.cpp

@@ -6,24 +6,29 @@
 
 #include <stdlib.h>
 
-extern "C" void __cxa_pure_virtual(void) {}
-extern "C" void __cxa_deleted_virtual(void) {}
-extern "C" int __cxa_atexit(void (*func) (void *), void * arg, void * dso_handle) {
+namespace std {
+  void __throw_length_error(const char* __s __attribute__((unused))) {}
+  void __throw_bad_alloc() {}
+  void __throw_bad_function_call() {}
+};
+
+extern "C" {
+
+void* __dso_handle = (void*) &__dso_handle;
+
+void __cxa_pure_virtual(void) {}
+void __cxa_deleted_virtual(void) {}
+int __cxa_atexit(void (*func) (void *), void * arg, void * dso_handle) {
   (void)func; (void)arg; (void)dso_handle; // unused
   return 0;
 }
-extern "C" int atexit(void (*func)(void)) {
+
+int atexit(void (*func)(void)) {
   (void)func;
   return 0;
 }
 
-namespace std {
-  void __throw_length_error(const char* __s __attribute__((unused))) {}
-  void __throw_bad_alloc() {}
-  void __throw_bad_function_call() {}
-};
-
-extern "C" int strcmp(const char* s1, const char* s2) {
+int strcmp(const char* s1, const char* s2) {
   while(*s1 && (*s1 == *s2))
   {
     s1++;
@@ -32,4 +37,4 @@ extern "C" int strcmp(const char* s1, const char* s2) {
   return *(const unsigned char*)s1 - *(const unsigned char*)s2;
 }
 
-extern "C" void* __dso_handle = (void*) &__dso_handle;
+} /* extern "C" */