Windows: support more Mingw-w64 versions

This reverts commit 295c1409f6.

config.nims

@@ -33,10 +33,15 @@ else:
     switch("passC", "-mno-avx512f")
     switch("passL", "-mno-avx512f")
 
-# omitting frame pointers in nim breaks the GC
+# Omitting frame pointers in nim breaks the GC:
 # https://github.com/nim-lang/Nim/issues/10625
-switch("passC", "-fno-omit-frame-pointer")
-switch("passL", "-fno-omit-frame-pointer")
+if not defined(windows):
+  # ...except on Windows where the Nim bug doesn't manifest and the option
+  # crashes GCC in some Mingw-w64 versions:
+  # https://sourceforge.net/p/mingw-w64/bugs/880/
+  # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86593
+  switch("passC", "-fno-omit-frame-pointer")
+  switch("passL", "-fno-omit-frame-pointer")
 
 --threads:on
 --opt:speed