POSIX: add a few constants for sysconf.

Change-Id: I400efdbccc97b287844917e21d8e08e26029f2f8
Reviewed-on: https://review.haiku-os.org/c/haiku/+/1839
Reviewed-by: waddlesplash <[email protected]>

headers/posix/unistd.h

@@ -131,6 +131,10 @@
 #define	_SC_TIMERS						58
 #define	_SC_CPUTIME						59
 #define	_SC_THREAD_CPUTIME				60
+#define _SC_HOST_NAME_MAX				61
+#define _SC_REGEXP						62
+#define _SC_SYMLOOP_MAX					63
+#define _SC_SHELL						64
 
 
 /* confstr() constants */

src/system/libroot/posix/unistd/conf.cpp

@@ -71,14 +71,22 @@ __sysconf(int name)
 			return CLK_TCK;
 		case _SC_JOB_CONTROL:
 			return 1;
+		case _SC_HOST_NAME_MAX:
+			return _POSIX_HOST_NAME_MAX;
 		case _SC_NGROUPS_MAX:
 			return NGROUPS_MAX;
 		case _SC_OPEN_MAX:
 			return getdtablesize();
+		case _SC_REGEXP:
+			return 1;
 		case _SC_SAVED_IDS:
 			return 1;
+		case _SC_SHELL:
+			return 1;
 		case _SC_STREAM_MAX:
 			return STREAM_MAX;
+		case _SC_SYMLOOP_MAX:
+			return SYMLOOP_MAX;
 		case _SC_TZNAME_MAX:
 			return TZNAME_MAX;
 		case _SC_VERSION: