mk: Package libstdc++-6.dll on x86_64 MinGW

We don't need the support libgcc SEH library, but we do need the C++ standard
library for running the compiler itself.

cc #29208

Author: alexcrichton

mk/dist.mk

@@ -150,11 +150,11 @@ prepare-overlay-$(1):
 
 dist/$$(PKG_NAME)-$(1).tar.gz: dist-install-dir-$(1)-host prepare-overlay-$(1)
 	@$(call E, build: $$@)
-# On a 32-bit MinGW target we've got a few runtime DLL dependencies that we need
+# On a MinGW target we've got a few runtime DLL dependencies that we need
 # to include. THe first argument to `make-win-dist` is where to put these DLLs
 # (the image we're creating) and the second argument is a junk directory to
 # ignore all the other MinGW stuff the script creates.
-ifeq ($(1),i686-pc-windows-gnu)
+ifeq ($$(findstring pc-windows-gnu,$(1)),pc-windows-gnu)
 	$$(Q)rm -Rf tmp/dist/win-rust-gcc-$(1)
 	$$(Q)$$(CFG_PYTHON) $$(S)src/etc/make-win-dist.py \
 		tmp/dist/$$(PKG_NAME)-$(1)-image \

src/etc/make-win-dist.py

@@ -50,8 +50,6 @@ def make_win_dist(rust_root, gcc_root, target_triple):
     rustc_dlls = ["libstdc++-6.dll"]
     if target_triple.startswith("i686-"):
         rustc_dlls.append("libgcc_s_dw2-1.dll")
-    else:
-        rustc_dlls.append("libgcc_s_seh-1.dll")
 
     target_libs = [ # MinGW libs
                     "crtbegin.o",