Remove nullability specifications.

Bug: http://b/64251432
Test: builds
Change-Id: I5b1613484783f7478d30b5e694007f77fa626659
diff --git a/libc/include/sys/swap.h b/libc/include/sys/swap.h
index 3444736..e79af97 100644
--- a/libc/include/sys/swap.h
+++ b/libc/include/sys/swap.h
@@ -38,8 +38,8 @@
 #define SWAP_FLAG_PRIO_MASK 0x7fff
 #define SWAP_FLAG_PRIO_SHIFT 0
 
-int swapon(const char* _Nonnull, int) __INTRODUCED_IN(19);
-int swapoff(const char* _Nonnull) __INTRODUCED_IN(19);
+int swapon(const char*, int) __INTRODUCED_IN(19);
+int swapoff(const char*) __INTRODUCED_IN(19);
 
 __END_DECLS