Make syslog thread-safe in --disable-gil builds

Feature or enhancement

The syslog module has two mutable global variables:

Lines 71 to 72 in 9dae05e

    
           static PyObject *S_ident_o = NULL;  // identifier, held by openlog() 
        
           static char S_log_open = 0;

We need to protect access to these variables in the --disable-gil builds.

pythongh-117440: Make `syslog` thread-safe in free-threaded builds

Merge branch 'pythongh-117440-syslog' into nogil-integration

gh-117440: Make `syslog` thread-safe in free-threaded builds (#117441)

pythongh-117440: Make `syslog` thread-safe in free-threaded builds (p…

	static PyObject *S_ident_o = NULL; // identifier, held by openlog()
	static char S_log_open = 0;