Potential issue with compiling on the HEAD of the branch

[work vlpl]

Hi, for my own needs, I am building freeradius from the HEAD
(d84dacda2d67fcffedb0dd75e97c71185eec37cb) of 3.0.x branch on
amazonlinux2. Because of that, I am not sure if this is a real problem
or just state between releases so I am not opening the issue in
GitHub.

The commit that is working for me is 9acf21e62de151918743de541567d13cd3e61f9a

Can you say if it is a real issue? If yes I will create a proper issue
in github.


```
In file included from src/main/threads.c:34:0:
src/main/threads.c: In function 'ssl_locking_function':
src/main/threads.c:256:28: error: invalid operands to binary != (have
'pthread_mutex_t {aka union <anonymous>}' and 'void *')
  rad_assert(ssl_mutexes[n] != NULL);
             ~~~~~~~~~~~~~~ ^
src/freeradius-devel/rad_assert.h:38:13: note: in definition of macro
'rad_assert'
   ((void) ((expr) ? (void) 0 : \
             ^~~~
make: *** [build/objs/src/main/threads.lo] Error 1
```


Best regards,
Vladimir