Bug in __register_exitproc() in __atexit.c

[Freddie Chopin]

Hello!

Today I noticed that even when I disable dynamic allocation of memory in 
atexit (with --disable-newlib-atexit-dynamic-alloc switch) malloc() is used in 
__register_exitproc().

First of all, if this switch is used, then _ATEXIT_DYNAMIC_ALLOC is not 
defined, so the first use of malloc() in this function - at line 93 - is 
indeed disabled. But if small reent is used, malloc() is used again at line 
120 - this time it's not conditional on _ATEXIT_DYNAMIC_ALLOC being defined.

Moreover, at first glance it seems that there's a bug in this function. The 
__atexit_lock lock is acquired at entry, but there are at two places where it 
is not released before return - at line 86 and at line 91.

Should I try to provide a patch for both issues?

Regards,
FCh