Merge pull request #3182 from vpeter4/build_verbose_flag

buildsystem: add flag to enable verbose build (if package support it)

config/functions

@@ -234,6 +234,12 @@ setup_toolchain() {
     export MAKEFLAGS="-j$CONCURRENCY_MAKE_LEVEL"
   fi
 
+  # verbose flag
+  if flag_enabled "verbose" "no"; then
+    NINJA_OPTS="$NINJA_OPTS -v"
+    export MAKEFLAGS="$MAKEFLAGS V=1 VERBOSE=1"
+  fi
+
   case "$1" in
     target|init)
       export DESTIMAGE="target"