[source] build: allow val.% targets to bypass the prepare steps

[LEDE Commits]

jow pushed a commit to source.git, branch lede-17.01:
https://git.lede-project.org/4607007a86cc240b091b9176b3d7aa82a6ca0c71

commit 4607007a86cc240b091b9176b3d7aa82a6ca0c71
Author: Felix Fietkau <nbd at nbd.name>
AuthorDate: Fri May 5 13:12:23 2017 +0200

    build: allow val.% targets to bypass the prepare steps
    
    Significantly reduces time spent processing those targets and should
    also silence some log clutter which could confuse buildbot
    
    Signed-off-by: Felix Fietkau <nbd at nbd.name>
    (cherry picked from commit ddbb036bbb8a1030dd8f6fae0004d390b5f2b8a5)
---
 include/toplevel.mk | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/include/toplevel.mk b/include/toplevel.mk
index 1171c59..8f967bd 100644
--- a/include/toplevel.mk
+++ b/include/toplevel.mk
@@ -183,6 +183,9 @@ prereq:: prepare-tmpinfo .config
 check: .config FORCE
 	@+$(NO_TRACE_MAKE) -r -s $@ QUIET= V=s
 
+val.%: FORCE
+	@+$(NO_TRACE_MAKE) -r -s $@ QUIET= V=s
+
 WARN_PARALLEL_ERROR = $(if $(BUILD_LOG),,$(and $(filter -j,$(MAKEFLAGS)),$(findstring s,$(OPENWRT_VERBOSE))))
 
 ifeq ($(SDK),1)