Update to v5.14 kernel headers.

Kernel headers coming from:

Git: https://android.googlesource.com/kernel/common/
Branch: android-mainline
Tag: android-mainline-5.14

Test: Builds, bionic unit tests.
Change-Id: Iff3424da9fbf7ae89ebeb6daabb34c4aa650901f
diff --git a/libc/kernel/uapi/linux/auxvec.h b/libc/kernel/uapi/linux/auxvec.h
index e8c2336..c80c170 100644
--- a/libc/kernel/uapi/linux/auxvec.h
+++ b/libc/kernel/uapi/linux/auxvec.h
@@ -42,4 +42,7 @@
 #define AT_RANDOM 25
 #define AT_HWCAP2 26
 #define AT_EXECFN 31
+#ifndef AT_MINSIGSTKSZ
+#define AT_MINSIGSTKSZ 51
+#endif
 #endif