msc-externals: Package msvc_dlls only necessary in 32-bit builds

In 64-bit builds the 64-bit runtimes are installed as MSM so this hack
isn't needed there.

Change-Id: Id609d2beaa3de1176138bc206210820397a8b732

external/msc-externals/Module_msc-externals.mk

@@ -9,8 +9,12 @@
 
 $(eval $(call gb_Module_Module,msc-externals))
 
+ifneq ($(BUILD_X64),)
+
 $(eval $(call gb_Module_add_targets,msc-externals,\
 	Package_msvc_dlls \
 ))
 
+endif
+
 # vim: set noet sw=4 ts=4: