Changes to Dalamud Boot DLL so that it works in WINE (#1111)

* Changes to Dalamud Boot DLL so that it works in WINE

* Make asm clearer

Dalamud.Boot/rewrite_entrypoint_thunks.asm

@@ -0,0 +1,82 @@
+PUBLIC EntryPointReplacement
+PUBLIC RewrittenEntryPoint_Standalone
+PUBLIC RewrittenEntryPoint
+
+; 06 and 07 are invalid opcodes
+; CC is int3 = bp
+; using 0CCCCCCCCCCCCCCCCh as function terminator
+; using 00606060606060606h as placeholders
+
+TERMINATOR = 0CCCCCCCCCCCCCCCCh
+PLACEHOLDER = 00606060606060606h
+
+.code
+
+EntryPointReplacement PROC
+    start:
+        ; rsp % 0x10 = 0x08
+        lea rax, [start]
+        push rax
+        
+        ; rsp % 0x10 = 0x00
+        mov rax, PLACEHOLDER
+
+        ; this calls RewrittenEntryPoint_Standalone
+        jmp rax
+
+    dq TERMINATOR
+EntryPointReplacement ENDP
+
+RewrittenEntryPoint_Standalone PROC
+    start:
+        ; stack is aligned to 0x10; see above
+        sub rsp, 20h
+        lea rcx, [embeddedData]
+        add rcx, qword ptr [nNethostOffset]
+        call qword ptr [pfnLoadLibraryW]
+        
+        lea rcx, [embeddedData]
+        add rcx, qword ptr [nDalamudOffset]
+        call qword ptr [pfnLoadLibraryW]
+        
+        mov rcx, rax
+        lea rdx, [pcszEntryPointName]
+        call qword ptr [pfnGetProcAddress]
+        
+        mov rcx, qword ptr [pRewrittenEntryPointParameters]
+        ; this calls RewrittenEntryPoint
+        jmp rax
+
+    pfnLoadLibraryW:
+        dq PLACEHOLDER
+
+    pfnGetProcAddress:
+        dq PLACEHOLDER
+
+    pRewrittenEntryPointParameters:
+        dq PLACEHOLDER
+
+    nNethostOffset:
+        dq PLACEHOLDER
+
+    nDalamudOffset:
+        dq PLACEHOLDER
+
+    pcszEntryPointName:
+        db "RewrittenEntryPoint", 0
+
+    embeddedData:
+    
+    dq TERMINATOR
+RewrittenEntryPoint_Standalone ENDP
+
+EXTERN RewrittenEntryPoint_AdjustedStack :PROC
+
+RewrittenEntryPoint PROC
+    ; stack is aligned to 0x10; see above
+    call RewrittenEntryPoint_AdjustedStack
+    add rsp, 20h
+    ret
+RewrittenEntryPoint ENDP
+
+END