No longer used hacked liveness_pass_1

This hack was introduced in issue#287 which later becomes endless maintainance pain.

=====

Our previous check_exit_request use `brcond` in the middle of a TranslationBlock which

breaks the assumptions and thus a hack to liveness_pass_1 is used for _all_ brcond instructions

which causes issues for MIPS and many other scenarios.

=====

This patch also resolves PC not sync-ed when no memory hooks are installed, finally. Now

Unicorn will always have correct PC no matter what happens.

tests/unit/test_mips.c

@@ -206,7 +206,7 @@ static void test_mips_simple_coredump_2134(void)
     const char code[] = "\x25\xc8\x80\x03\x25\x78\xe0\x03\x09\xf8\x20\x03\x10\x00\x18\x24";
     uc_common_setup(&uc, UC_ARCH_MIPS, UC_MODE_MIPS32, code, sizeof(code) - 1);
 
-    OK(uc_emu_start(uc, code_start, code_start + sizeof(code) - 1, 0, 0));
+    uc_assert_err(uc_emu_start(uc, code_start, code_start + sizeof(code) - 1, 0, 0), UC_ERR_FETCH_UNMAPPED);
 
     OK(uc_close(uc));
 }