Use kernel-provided __NR_getrandom syscall number

Replace libc's SYS_getrandom with the kernel-provided __NR_getrandom
in configure checks, os.getrandom(), and interpreter entropy handling.

Author: jjhelmus

Modules/posixmodule.c

@@ -17440,7 +17440,7 @@ os_getrandom_impl(PyObject *module, Py_ssize_t size, unsigned int flags)
 #ifdef HAVE_GETRANDOM
         n = getrandom(data, size, flags);
 #else
-        n = syscall(SYS_getrandom, data, size, flags);
+        n = syscall(__NR_getrandom, data, size, flags);
 #endif
         if (n < 0 && errno == EINTR) {
             if (PyErr_CheckSignals() < 0) {

Python/bootstrap_hash.c

@@ -23,7 +23,7 @@
 #    include <sys/random.h>       // getrandom()
 #  endif
 #  if !defined(HAVE_GETRANDOM) && defined(HAVE_GETRANDOM_SYSCALL)
-#    include <sys/syscall.h>      // SYS_getrandom
+#    include <sys/syscall.h>      // __NR_getrandom
 #  endif
 #endif
 
@@ -128,11 +128,11 @@ py_getrandom(void *buffer, Py_ssize_t size, int blocking, int raise)
 #else
         if (raise) {
             Py_BEGIN_ALLOW_THREADS
-            n = syscall(SYS_getrandom, dest, n, flags);
+            n = syscall(__NR_getrandom, dest, n, flags);
             Py_END_ALLOW_THREADS
         }
         else {
-            n = syscall(SYS_getrandom, dest, n, flags);
+            n = syscall(__NR_getrandom, dest, n, flags);
         }
 #  ifdef _Py_MEMORY_SANITIZER
         if (n > 0) {

configure

@@ -7812,7 +7812,7 @@ AC_LINK_IFELSE(
         const size_t buflen = sizeof(buffer);
         const int flags = GRND_NONBLOCK;
         /* ignore the result, Python checks for ENOSYS and EAGAIN at runtime */
-        (void)syscall(SYS_getrandom, buffer, buflen, flags);
+        (void)syscall(__NR_getrandom, buffer, buflen, flags);
         return 0;
     }
   ]])