kbuild: modpost on vmlinux regardless of CONFIG_MODULES

Based on patch from: Magnus Damm <magnus@valinux.co.jp>
This has the advantage that all section mismatch checks are run regardless
of modules being enabled or not.

When running modpost on vmlinux output:
MODPOST vmlinux

When running modpost on modules output count of modules like this:
MODPOST 5 modules

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
diff --git a/scripts/Makefile b/scripts/Makefile
index d531a1f..ea41de8 100644
--- a/scripts/Makefile
+++ b/scripts/Makefile
@@ -19,7 +19,7 @@
 hostprogs-y += unifdef
 
 subdir-$(CONFIG_MODVERSIONS) += genksyms
-subdir-$(CONFIG_MODULES)     += mod
+subdir-y                     += mod
 
 # Let clean descend into subdirs
 subdir-	+= basic kconfig package