Add regress test for issue #334

https://github.com/unicorn-engine/unicorn/issues/334

The code is a bit different than in the issue, but it should demonstrate the main problem just fine.

tests/regress/hook_code_add_del.py

@@ -0,0 +1,48 @@
+#!/usr/bin/python
+
+'''https://github.com/unicorn-engine/unicorn/issues/334'''
+
+from __future__ import print_function
+import regress
+
+from unicorn import *
+from unicorn.x86_const import *
+
+ADDRESS = 0x8048000
+STACK_ADDRESS = 0xffff000
+STACK_SIZE = 4096
+'''
+31 DB           xor ebx, ebx
+53              push ebx
+43              inc ebx
+53              push ebx
+6A 02           push 2
+6A 66           push 66h
+58              pop eax
+89 E1           mov ecx, esp
+CD 80           int 80h
+'''
+CODE = "\x31\xDB\x53\x43\x53\x6A\x02\x6A\x66\x58\x89\xE1\xCD\x80"
+EP = ADDRESS + 0x54
+
+def hook_code(mu, address, size, user_data):
+        print(">>> Tracing instruction at 0x%x, instruction size = %u" %(address, size))
+        
+class HookCodeAddDelTest(regress.RegressTest):
+        def runTest(self):
+                emu = Uc(UC_ARCH_X86, UC_MODE_32)
+                emu.mem_map(ADDRESS, 0x1000)
+                emu.mem_write(EP, CODE)
+
+                emu.mem_map(STACK_ADDRESS, STACK_SIZE)
+                emu.reg_write(UC_X86_REG_ESP, STACK_ADDRESS + STACK_SIZE)
+                
+                # UC_HOOK_CODE hook will work even after deletion
+                emu.hook_add(UC_HOOK_CODE, hook_code, None)
+                emu.hook_del(UC_HOOK_CODE)
+                
+                emu.emu_start(EP, EP + len(CODE), count = 3)
+                print("EIP: 0x%x" % emu.reg_read(UC_X86_REG_EIP))
+                
+if __name__ == '__main__':
+        regress.main()