kbuild: removing .tmp_versions considered harmful

Remove *.mod files but not .tmp_versions for external builds

When "make install" is run as root, .tmp_versions is re-created and
becomes owned by root.  Subsequent "make" run by user fails because
.tmp_versions cannot be removed.
Signed-off-by: Pavel Roskin <proski@gnu.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

Makefile

@@ -796,8 +796,8 @@ prepare2: prepare3 outputmakefile
 prepare1: prepare2 include/linux/version.h include/asm \
                    include/config/MARKER
 ifneq ($(KBUILD_MODULES),)
-	$(Q)rm -rf $(MODVERDIR)
 	$(Q)mkdir -p $(MODVERDIR)
+	$(Q)rm -f $(MODVERDIR)/*
 endif
 
 archprepare: prepare1 scripts_basic
@@ -1086,8 +1086,8 @@ else # KBUILD_EXTMOD
 KBUILD_MODULES := 1
 PHONY += crmodverdir
 crmodverdir:
-	$(Q)rm -rf $(MODVERDIR)
 	$(Q)mkdir -p $(MODVERDIR)
+	$(Q)rm -f $(MODVERDIR)/*
 
 PHONY += $(objtree)/Module.symvers
 $(objtree)/Module.symvers: