Misc: Fix build with MinGW when using IMGUI_API.

imgui.h

@@ -64,7 +64,7 @@ Index of this file:
 // Version
 // (Integer encoded as XYYZZ for use in #if preprocessor conditionals. Work in progress versions typically starts at XYY99 then bounce up to XYY00, XYY01 etc. when release tagging happens)
 #define IMGUI_VERSION               "1.85"
-#define IMGUI_VERSION_NUM           18500
+#define IMGUI_VERSION_NUM           18501
 #define IMGUI_CHECKVERSION()        ImGui::DebugCheckVersionAndDataLayout(IMGUI_VERSION, sizeof(ImGuiIO), sizeof(ImGuiStyle), sizeof(ImVec2), sizeof(ImVec4), sizeof(ImDrawVert), sizeof(ImDrawIdx))
 #define IMGUI_HAS_TABLE
 

imgui_internal.h

@@ -2192,7 +2192,7 @@ struct ImGuiTableCellData
 };
 
 // FIXME-TABLE: more transient data could be stored in a per-stacked table structure: DrawSplitter, SortSpecs, incoming RowData
-struct ImGuiTable
+struct IMGUI_API ImGuiTable
 {
     ImGuiID                     ID;
     ImGuiTableFlags             Flags;
@@ -2298,14 +2298,14 @@ struct ImGuiTable
     bool                        MemoryCompacted;
     bool                        HostSkipItems;              // Backup of InnerWindow->SkipItem at the end of BeginTable(), because we will overwrite InnerWindow->SkipItem on a per-column basis
 
-    IMGUI_API ImGuiTable()      { memset(this, 0, sizeof(*this)); LastFrameActive = -1; }
-    IMGUI_API ~ImGuiTable()     { IM_FREE(RawData); }
+    ImGuiTable()                { memset(this, 0, sizeof(*this)); LastFrameActive = -1; }
+    ~ImGuiTable()               { IM_FREE(RawData); }
 };
 
 // Transient data that are only needed between BeginTable() and EndTable(), those buffers are shared (1 per level of stacked table).
 // - Accessing those requires chasing an extra pointer so for very frequently used data we leave them in the main table structure.
 // - We also leave out of this structure data that tend to be particularly useful for debugging/metrics.
-struct ImGuiTableTempData
+struct IMGUI_API ImGuiTableTempData
 {
     int                         TableIndex;                 // Index in g.Tables.Buf[] pool
     float                       LastTimeActive;             // Last timestamp this structure was used
@@ -2322,7 +2322,7 @@ struct ImGuiTableTempData
     float                       HostBackupItemWidth;        // Backup of OuterWindow->DC.ItemWidth at the end of BeginTable()
     int                         HostBackupItemWidthStackSize;//Backup of OuterWindow->DC.ItemWidthStack.Size at the end of BeginTable()
 
-    IMGUI_API ImGuiTableTempData() { memset(this, 0, sizeof(*this)); LastTimeActive = -1.0f; }
+    ImGuiTableTempData()        { memset(this, 0, sizeof(*this)); LastTimeActive = -1.0f; }
 };
 
 // sizeof() ~ 12