[libc++abi] Change __cxa_finalize return type to void

Summary:
The return type of __cxa_finalize is documented as void in the Itanium
C++ ABI, and it is void in various C libraries.

Reviewers: EricWF, ldionne, compnerd, mclow.lists, MaskRay

Reviewed By: MaskRay

Subscribers: MaskRay, dexonsmith, ldionne, libcxx-commits

Tags: #libc

Differential Revision: https://reviews.llvm.org/D75795

libcxxabi/include/cxxabi.h

@@ -138,7 +138,7 @@ __cxa_vec_cctor(void *dest_array, void *src_array, size_t element_count,
 // 3.3.5.3 Runtime API
 extern _LIBCXXABI_FUNC_VIS int __cxa_atexit(void (*f)(void *), void *p,
                                             void *d);
-extern _LIBCXXABI_FUNC_VIS int __cxa_finalize(void *);
+extern _LIBCXXABI_FUNC_VIS void __cxa_finalize(void *);
 
 // 3.4 Demangler API
 extern _LIBCXXABI_FUNC_VIS char *__cxa_demangle(const char *mangled_name,