build: Pass V=1 to selftests build if VERBOSE is set

The selftests build now uses V=1 to show the actual command being run,
since kernel commit 6fc6d7f59376 ("selftests: adopt BPF's approach to
quieter builds").

Author: mpe

build/scripts/container-build.sh

@@ -179,7 +179,7 @@ else
     # Workaround 303e6218ecec ("selftests: Fix O= and KBUILD_OUTPUT handling for relative paths")
     export abs_objtree=$KBUILD_OUTPUT
 
-    cmd="make -k $quiet -j $JFACTOR -C tools/testing/selftests"
+    cmd="make -k $quiet $verbose -j $JFACTOR -C tools/testing/selftests"
 
     if [[ "$1" == "ppctests" ]]; then
         TARGETS="powerpc"