libbpf: Fix arm syscall regs spec in bpf_tracing.h

The syscall register definitions for ARM in bpf_tracing.h doesn't define
the fifth parameter for the syscalls. Because of this some KPROBES based
selftests fail to compile for ARM architecture.

Define the fifth parameter that is passed in the R5 register (uregs[4]).

Fixes: 3a95c42 ("libbpf: Define arm syscall regs spec in bpf_tracing.h")
Signed-off-by: Puranjay Mohan <puranjay12@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20230223095346.10129-1-puranjay12@gmail.com

tools/lib/bpf/bpf_tracing.h

@@ -204,6 +204,7 @@ struct pt_regs___s390 {
 #define __PT_PARM2_SYSCALL_REG __PT_PARM2_REG
 #define __PT_PARM3_SYSCALL_REG __PT_PARM3_REG
 #define __PT_PARM4_SYSCALL_REG __PT_PARM4_REG
+#define __PT_PARM5_SYSCALL_REG uregs[4]
 #define __PT_PARM6_SYSCALL_REG uregs[5]
 #define __PT_PARM7_SYSCALL_REG uregs[6]