[libc++/abi] Re-remove unnecessary null pointer checks from operator delete

[ldionne]

Summary

In 7cd67904f776, we removed the unnecessary nullptr checks from the libc++abi
definition of operator delete, but we forgot to update the definition in
libc++ (damn code duplication!). Then, in d4a1e03c5fb5, I synced the
definitions across libc++ and libc++abi, but I did it the wrong way around.
I re-added the if() checks to libc++abi instead of removing them from libc++.

In ef74f0fdc339, we re-removed the if() check from operator delete, but
only in libc++abi. This patch corrects this mess and removes it
consistently in libc++ and libc++abi.

[MaskRay]

Looks great!

libcxx/src/new.cpp

 #endif  // _LIBCPP_NO_EXCEPTIONS
     return p;
 }
 
 _LIBCPP_WEAK
 void
 operator delete(void* ptr) _NOEXCEPT
 {
-    if (ptr)
-        ::free(ptr);
 }
 
 _LIBCPP_WEAK
 void
 operator delete(void* ptr, const std::nothrow_t&) _NOEXCEPT
 {
     ::operator delete(ptr);
 }

 #endif  // _LIBCPP_NO_EXCEPTIONS
     return p;
 }
 
 _LIBCPP_WEAK
 void
 operator delete(void* ptr, std::align_val_t) _NOEXCEPT
 {
-    if (ptr) {
-        std::__libcpp_aligned_free(ptr);
-    }
-}
 
 _LIBCPP_WEAK
 void
 operator delete(void* ptr, std::align_val_t alignment, const std::nothrow_t&) _NOEXCEPT
 {
     ::operator delete(ptr, alignment);
 }
 

libcxxabi/src/stdlib_new_delete.cpp

 #endif  // _LIBCXXABI_NO_EXCEPTIONS
     return p;
 }
 
 _LIBCXXABI_WEAK
 void
 operator delete(void* ptr, std::align_val_t) _NOEXCEPT
 {
-    if (ptr) {
-        std::__libcpp_aligned_free(ptr);
-    }
-}
 
 _LIBCXXABI_WEAK
 void
 operator delete(void* ptr, std::align_val_t alignment, const std::nothrow_t&) _NOEXCEPT
 {
     ::operator delete(ptr, alignment);
 }