Remove the useless _C_LABEL from generated system calls.

Change-Id: Id1d2fd39972652831ea825f6f9cf940b08f42b5c
diff --git a/libc/arch-mips64/syscalls/__rt_sigsuspend.S b/libc/arch-mips64/syscalls/__rt_sigsuspend.S
index 943311f..f36e1c3 100644
--- a/libc/arch-mips64/syscalls/__rt_sigsuspend.S
+++ b/libc/arch-mips64/syscalls/__rt_sigsuspend.S
@@ -23,4 +23,4 @@
     move ra, t0
     .set pop
 END(__rt_sigsuspend)
-.hidden _C_LABEL(__rt_sigsuspend)
+.hidden __rt_sigsuspend