ignore ENOSYS error from mprotect in pthread_create and dynamic linker

this error simply indicated a system without memory protection (NOMMU)
and should not cause failure in the caller.
diff --git a/src/thread/pthread_create.c b/src/thread/pthread_create.c
index 6e2e481..e7df34a 100644
--- a/src/thread/pthread_create.c
+++ b/src/thread/pthread_create.c
@@ -232,7 +232,8 @@
 		if (guard) {
 			map = __mmap(0, size, PROT_NONE, MAP_PRIVATE|MAP_ANON, -1, 0);
 			if (map == MAP_FAILED) goto fail;
-			if (__mprotect(map+guard, size-guard, PROT_READ|PROT_WRITE)) {
+			if (__mprotect(map+guard, size-guard, PROT_READ|PROT_WRITE)
+			    && errno != ENOSYS) {
 				__munmap(map, size);
 				goto fail;
 			}