test/bpf: add new test cases

test/bpf: add new test cases

This patch implements following new test cases:
- test_call4: test case to verify if stack corruption occurs
across with multiple function calls.
- test_jump2: test case with a default packet in memory, parse
the packet and check if dest ip is part of a subnet.
- test_call5: test case with string data in the stack and
calling string comaprision.

Signed-off-by: Harman Kalra <hkalra@marvell.com>
Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>