kbuild: silence mystery message

During last phase of the build the following message were displayed:
/bin/sh: +@: command not found

This message appears due to slightly changed semantics
of cmd and if_changed_rule.
The easy fix was to insert a dummy command first in rule_ksym_ld.
The alternative was to redo part of this processing in the top-level
Makefile - a volatile area that I try to avoid.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
---

1 files changed, 2 insertions, 0 deletions

diff --git a/Makefile b/Makefile
index 2467aa0f6689..06995fe7f57c 100644
--- a/Makefile
+++ b/Makefile
@@ -688,8 +688,10 @@ endef
 
 # Update vmlinux version before link
 # Use + in front of this rule to silent warning about make -j1
+# First command is ':' to allow us to use + in front of this rule
 cmd_ksym_ld = $(cmd_vmlinux__)
 define rule_ksym_ld
+        : 
         +$(call cmd,vmlinux_version)
         $(call cmd,vmlinux__)
         $(Q)echo 'cmd_$@ := $(cmd_vmlinux__)' > $(@D)/.$(@F).cmd