riscv64: use L() in the handful of places we didn't already.

Change-Id: If34ae7a0eb3f7d0bd84018de4b987fd437decf58
diff --git a/libc/arch-riscv64/bionic/__bionic_clone.S b/libc/arch-riscv64/bionic/__bionic_clone.S
index 2827857..be386b1 100644
--- a/libc/arch-riscv64/bionic/__bionic_clone.S
+++ b/libc/arch-riscv64/bionic/__bionic_clone.S
@@ -41,19 +41,19 @@
   ecall
 
   # Are we the child?
-  beqz a0, .L_bc_child
+  beqz a0, L(child)
 
   # Did the clone(2) fail?
-  bltz a0, .L_bc_failure
+  bltz a0, L(failure)
   # Nope, we're the parent, and our work here is done.
   ret
 
-.L_bc_failure:
+L(failure):
   # Set errno if something went wrong.
   neg a0, a0
   tail __set_errno_internal
 
-.L_bc_child:
+L(child):
   # We're in the child now. Set the end of the frame record chain.
   li fp, 0
   # Setting ra to 0 will make the unwinder stop at __start_thread.