Update to v4.17.3 kernel headers.

Test: Builds, boots on a walleye.
Change-Id: I389d8b61ec00ea309e38d1b1a2e0dace48c21edb
diff --git a/libc/kernel/uapi/asm-generic/mman-common.h b/libc/kernel/uapi/asm-generic/mman-common.h
index e752bb6..6f688a1 100644
--- a/libc/kernel/uapi/asm-generic/mman-common.h
+++ b/libc/kernel/uapi/asm-generic/mman-common.h
@@ -32,6 +32,7 @@
 #define MAP_FIXED 0x10
 #define MAP_ANONYMOUS 0x20
 #define MAP_UNINITIALIZED 0x0
+#define MAP_FIXED_NOREPLACE 0x100000
 #define MLOCK_ONFAULT 0x01
 #define MS_ASYNC 1
 #define MS_INVALIDATE 2