basic/macros: rename noreturn into _noreturn_ (#8456)

"noreturn" is reserved and can be used in other header files we include:

  [   16s] In file included from /usr/include/gcrypt.h:30:0,
  [   16s]                  from ../src/journal/journal-file.h:26,
  [   16s]                  from ../src/journal/journal-vacuum.c:31:
  [   16s] /usr/include/gpg-error.h:1544:46: error: expected ‘,’ or ‘;’ before ‘)’ token
  [   16s]  void gpgrt_log_bug (const char *fmt, ...)    GPGRT_ATTR_NR_PRINTF(1,2);

Here we include grcrypt.h (which in turns include gpg-error.h) *after* we
"noreturn" was defined in macro.h.

src/basic/log.h

@@ -186,7 +186,7 @@ int log_dump_internal(
                 char *buffer);
 
 /* Logging for various assertions */
-noreturn void log_assert_failed_realm(
+_noreturn_ void log_assert_failed_realm(
                 LogRealm realm,
                 const char *text,
                 const char *file,
@@ -195,7 +195,7 @@ noreturn void log_assert_failed_realm(
 #define log_assert_failed(text, ...) \
         log_assert_failed_realm(LOG_REALM, (text), __VA_ARGS__)
 
-noreturn void log_assert_failed_unreachable_realm(
+_noreturn_ void log_assert_failed_unreachable_realm(
                 LogRealm realm,
                 const char *text,
                 const char *file,