Make SIGRTMIN hide the real-time signals we use internally.

__SIGRTMIN will continue to tell the truth. This matches glibc's
behavior (as evidenced by the fact that we don't need a special case
in the strsignal test now).

Change-Id: I1abe1681d516577afa8cd39c837ef12467f68dd2
diff --git a/libc/kernel/uapi/asm-mips/asm/signal.h b/libc/kernel/uapi/asm-mips/asm/signal.h
index 53f5015..b774a66 100644
--- a/libc/kernel/uapi/asm-mips/asm/signal.h
+++ b/libc/kernel/uapi/asm-mips/asm/signal.h
@@ -71,8 +71,8 @@
 #define SIGXCPU 30
 #define SIGXFSZ 31
 /* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
-#define SIGRTMIN 32
-#define SIGRTMAX _KERNEL__NSIG
+#define __SIGRTMIN 32
+#define __SIGRTMAX _KERNEL__NSIG
 #define SA_ONSTACK 0x08000000
 #define SA_RESETHAND 0x80000000
 /* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */