gbuild: tweak var2file so it handles some shell metacharacters

Always quote the passed string; this cannot handle arbitrary strings
like $(file) can, but everything that is needed currently.

Also, try to ensure that output does not start with a space.

Note: there needs to be a newline at the end, otherwise helpex
ignores the last item on the line.

Change-Id: I51a4058591cc4f12dd878c2d113bd5cfc8c22d61

solenv/gbuild/Tempfile.mk

@@ -29,13 +29,14 @@ else
 define var2file
 $(strip $(1)
 $(eval gb_var2file_helpervar := $$(shell printf "%s" "" > $(1) ))\
-$(foreach item,$(3),$(eval gb_var2file_curblock += $(item)
+$(eval gb_var2file_curblock := $(firstword $(3)))\
+$(foreach item,$(wordlist 2,99999,$(3)),$(eval gb_var2file_curblock += $(item)
 	ifeq ($$(words $$(gb_var2file_curblock)),$(2)) 
 		gb_var2file_helpervar := $$(shell printf "%s" "$$(gb_var2file_curblock)" >> $(1) )
 		gb_var2file_curblock :=
 	endif
 	))\
-	$(eval gb_var2file_helpervar := $(shell echo " "$(gb_var2file_curblock) >> $(1) )
+	$(eval gb_var2file_helpervar := $(shell printf "%s\n" "$(gb_var2file_curblock)" >> $(1) )
 		gb_var2file_curblock :=
 	))
 endef