AP_Common: override new and delete on all platforms to zero memory

this guarantees that all classes get zero initial members when
they are dynamically allocated.

libraries/AP_Common/c++.cpp

@@ -9,10 +9,18 @@
 #include <AP_HAL.h>
 #include <stdlib.h>
 
-#if CONFIG_HAL_BOARD == HAL_BOARD_APM1 || CONFIG_HAL_BOARD == HAL_BOARD_APM2 || CONFIG_HAL_BOARD == HAL_BOARD_FLYMAPLE
-
+/*
+  globally override new and delete to ensure that we always start with
+  zero memory. This ensures consistent behaviour. Note that
+  initialising all members of all C++ classes separately takes a lot
+  of flash space. On APM1/APM2 it would mean we wouldn't fit on the
+  board at all.
+ */
 void * operator new(size_t size)
 {
+    if (size < 1) {
+        size = 1;
+    }
     return(calloc(size, 1));
 }
 
@@ -21,15 +29,11 @@ void operator delete(void *p)
     if (p) free(p);
 }
 
-// Conflicts with libmaple wirish/cxxabi-compat.cpp
-#if CONFIG_HAL_BOARD != HAL_BOARD_FLYMAPLE
-extern "C" void __cxa_pure_virtual(){
-    while (1){}
-}
-#endif
-
 void * operator new[](size_t size)
 {
+    if (size < 1) {
+        size = 1;
+    }
     return(calloc(size, 1));
 }
 
@@ -38,6 +42,16 @@ void operator delete[](void * ptr)
     if (ptr) free(ptr);
 }
 
+
+#if CONFIG_HAL_BOARD == HAL_BOARD_APM1 || CONFIG_HAL_BOARD == HAL_BOARD_APM2 || CONFIG_HAL_BOARD == HAL_BOARD_FLYMAPLE
+
+// Conflicts with libmaple wirish/cxxabi-compat.cpp
+#if CONFIG_HAL_BOARD != HAL_BOARD_FLYMAPLE
+extern "C" void __cxa_pure_virtual(){
+    while (1){}
+}
+#endif
+
 __extension__ typedef int __guard __attribute__((mode (__DI__)));
 
 int __cxa_guard_acquire(__guard *g)