Fix thread support (#640)

This PR fixes several things related to threads emulation:

1. Support `SameTebFlags.InitialThread`
This flag is needed to support emulation of .net executables (not yet
fully supported) that don't have an entry point set in `PE` header. This
applies to both `PE32` and `PE64` executables. If `InitialThread` is set
the loader substitutes an entry point of the .net executable with
`mscoree.dll!_CorExeMain`.

2. Fix static thread local storage for `WOW64`
This fix resolves `shell32.dll` initialization on `WOW64`. This fix also
uses correct structure and field names that are obtained from the
corresponding `.pdb` files.

3. Fix dynamic thread local storage for `WOW64`

4. Fix setting argument of a `WOW64` thread start proc

5. Fix creating suspended thread and parse create_flags
Currently creating suspended thread doesn't work because
`NtCreateThreadEx` handler uses invalid flag `CREATE_SUSPENDED`. This PR
fixes that, and moreover it carefully parses create_flags of the
`NtCreateThreadEx` call.

6. Fix `FS` and `GS` handling
This PR fixes several problems with `GS` and `FS` segments:

    * Wrong GDT descriptor for selector 0x53
* Update GDT descriptor for selector 0x53 for a `WOW64` process every
context switch like Windows does
* Set `GS` base when `GS` segment register is updated in 64-bit code
(code selector is `0x33`). When `GS` segment register is loaded with
correct selector (`0x2b`) `GS` base is set to 0. So, when the code
accesses something like `gs:[0]`, a page fault occurs. `KiPageFault`
handles this situation and sets correct `GS` base.

Also, take into account that `teb64.ExceptionList` initially contains
`teb32` address for `WOW64` process. This is used to setup `FS` base
when `wrfsbase` instruction is available. We can enable this instruction
using `kusd.ProcessorFeatures.arr[PF_RDWRFSGSBASE_AVAILABLE] = 1;` and
this work perfectly with `unicorn` backend. Unfortunately `icicle`
backend does not support `wrfsbase`, so I don't enable this instruction
by default.

src/emulator/arch_emulator.hpp

@@ -35,6 +35,7 @@ struct x86_emulator : arch_emulator<Traits>
     using pointer_type = typename Traits::pointer_type;
 
     virtual void set_segment_base(register_type base, pointer_type value) = 0;
+    virtual pointer_type get_segment_base(register_type base) = 0;
     virtual void load_gdt(pointer_type address, uint32_t limit) = 0;
 };
 

src/emulator/hook_interface.hpp

@@ -16,10 +16,11 @@ enum class instruction_hook_continuation : bool
     skip_instruction = true,
 };
 
-enum class memory_violation_continuation : bool
+enum class memory_violation_continuation : uint8_t
 {
-    stop = false,
-    resume = true,
+    stop,
+    resume,
+    restart,
 };
 
 enum class memory_violation_type : uint8_t