[PATCH] kbuild: Smart notation for non-verbose output

Create a nice shorthand to enable the non-verbose output mode.
make V=1        => Gives verbose output (default)
make V=0        => Gives non-verbose output

One of the reasons why people does not use KBUILD_VERBOSE=0 that
much is simply the typing needed.
This notation should make it acceptable to type it.
The usage of "make V=0" is restricted to the command line.
Anyone that wants to enable the non-verbose mode pr. default shall
set KBUILD_VERBOSE in the shell.

Makefile

@@ -107,6 +107,11 @@ export KBUILD_MODULES KBUILD_BUILTIN KBUILD_VERBOSE
 
 #	For now, leave verbose as default
 
+ifdef V
+  ifeq ("$(origin V)", "command line")
+    KBUILD_VERBOSE = $(V)
+  endif
+endif
 ifndef KBUILD_VERBOSE
   KBUILD_VERBOSE = 1
 endif