Increase stack size for eBPF programs to 512 bytes (#197)

Signed-off-by: Alan Jowett <alanjo@microsoft.com>

external/ubpf

@@ -1 +1 @@
-Subproject commit 6492b7a9363ea1e32194a95b66617df0f7fd42de
+Subproject commit c7c019c507c09c20243c5cbaf535d73a979aec23

libs/ubpf/kernel/ubpf_kernel.c

@@ -30,4 +30,6 @@
 #define stderr 0
 #define fprintf NULL
 
+#define UBPF_STACK_SIZE 512
+
 #include "ubpf_vm.c"

libs/ubpf/user/ubpf_user.c

@@ -14,6 +14,7 @@
 #pragma warning(disable : 4267)
 
 #include <endian.h>
+#define UBPF_STACK_SIZE 512
 
 #include "ubpf_jit_x86_64.c"
 #include "ubpf_vm.c"