Windows: Configure MinGW LTO with -fno-use-linker-plugin -fwhole-program

- Works around and closes godotengine#102867.
- Works around and closes godotengine#102982.

Co-authored-by: Hein-Pieter van Braam-Stewart <hp@tmm.cx>

Author: akien-mga

platform/windows/detect.py

@@ -779,8 +779,9 @@ def configure_mingw(env: "SConsEnvironment"):
             env.Append(CCFLAGS=["-flto"])
             env.Append(LINKFLAGS=["-flto=" + str(env.GetOption("num_jobs"))])
         else:
-            env.Append(CCFLAGS=["-flto"])
-            env.Append(LINKFLAGS=["-flto"])
+            # For mingw-gcc LTO, disable linker plugin and enable whole program to work around GH-102867.
+            env.Append(CCFLAGS=["-flto", "-fno-use-linker-plugin", "-fwhole-program"])
+            env.Append(LINKFLAGS=["-flto", "-fno-use-linker-plugin", "-fwhole-program"])
 
     if env["use_asan"]:
         env.Append(LINKFLAGS=["-Wl,--stack," + str(STACK_SIZE_SANITIZERS)])