use LLVM_INSTALL for BB on Windows

[ci skip]

Author: vchuravy

deps/llvm.mk

@@ -581,7 +581,12 @@ $(BUILDDIR)/llvm-$(LLVM_VER)-$(LLVM_BB_REL)/LLVM.$(BB_TRIPLET).tar.gz: | $(BUILD
 $(BUILDDIR)/llvm-$(LLVM_VER)-$(LLVM_BB_REL)/build-compiled: | $(BUILDDIR)/llvm-$(LLVM_VER)-$(LLVM_BB_REL)/LLVM.$(BB_TRIPLET).tar.gz
 	echo 1 > $@
 
-$(eval $(call staged-install,llvm,llvm-$$(LLVM_VER)-$$(LLVM_BB_REL),,,,))
+LLVM_INSTALL =
+ifeq ($(OS), WINNT)
+LLVM_INSTALL += cp $2$$(build_shlibdir)/LLVM.dll $2$$(build_depsbindir)
+endif
+
+$(eval $(call staged-install,llvm,llvm-$$(LLVM_VER)-$$(LLVM_BB_REL),LLVM_INSTALL,,,))
 
 #Override provision of stage tarball
 $(build_staging)/llvm-$(LLVM_VER)-$(LLVM_BB_REL).tgz: $(BUILDDIR)/llvm-$(LLVM_VER)-$(LLVM_BB_REL)/build-compiled