libc: fix executable destruction support.

This change allows an executable to call its destructor functions
(declared with __attribute__((destructor))) to be properly called
when it normally exits.

Note that this is different from calling the destructors of a shared
library when it is unloaded with dlclose() or through program exit,
which are already supported.

Bug: 3106500
Change-Id: I1412ef5407f13b613fc6cb6103e0a691dbee4b1a

libc/bionic/libc_init_common.h

@@ -39,5 +39,6 @@ typedef struct
 } structors_array_t;
 
 extern void __libc_init_common(uintptr_t *elfdata);
+extern void __libc_fini(void* finit_array);
 
 #endif