Unix build: for mingw and cygwin, create the right location for DLLs

Mingw and Cygwin builds install the DLLs in the application directory,
not the library directory, so ensure that one is created for them when
installing the DLLs.

Fixes #7653
Reviewed-by: NTim Hudson <tjh@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/7654)

(cherry picked from commit 9694ebf753e571a55935a63b4df8016e7bd3248d)

Configurations/unix-Makefile.tmpl

@@ -640,7 +640,9 @@ install_runtime_libs: build_libs
 	@[ -n "$(INSTALLTOP)" ] || (echo INSTALLTOP should not be empty; exit 1)
 	@ : {- output_off() if windowsdll(); "" -}
 	@$(PERL) $(SRCDIR)/util/mkdir-p.pl $(DESTDIR)$(libdir)
-	@ : {- output_on() if windowsdll(); "" -}
+	@ : {- output_on() if windowsdll(); output_off() unless windowsdll(); "" -}
+	@$(PERL) $(SRCDIR)/util/mkdir-p.pl $(DESTDIR)$(INSTALLTOP)/bin
+	@ : {- output_on() unless windowsdll(); "" -}
 	@$(ECHO) "*** Installing runtime libraries"
 	@set -e; for s in dummy $(INSTALL_SHLIBS); do \
 		if [ "$$s" = "dummy" ]; then continue; fi; \