sparc: disable cancellable system, as it fails in strange ways right now

Signed-off-by: Austin Foxley <austinf@cetoncorp.com>

libc/stdlib/system.c

@@ -18,7 +18,10 @@
 #endif
 
 
-#if !defined __UCLIBC_HAS_THREADS_NATIVE__
+/* TODO: the cancellable version breaks on sparc currently,
+ * need to figure out why still
+ */
+#if !defined __UCLIBC_HAS_THREADS_NATIVE__ || defined __sparc__
 /* uClinux-2.0 has vfork, but Linux 2.0 doesn't */
 #include <sys/syscall.h>
 #ifndef __NR_vfork