debuginfo: Allow kbuilds with the output directory

Consider another directory level when searching for vmlinux, for kernel
builds in sub-directory using `make O=output_dir'. Also, improve warning
message making it more understandable.

scripts/process-debuginfo.in

@@ -31,14 +31,14 @@ elif [ -z "${f#./lib/modules/*.ko.[gx]z}" ]; then
 elif [ -z "${f##./boot/vmlinuz-*}" ]; then
 	# Compressed kernel: trigger extraction of vmlinux from the source.
 	kver=${f#./boot/vmlinuz-}
-	vmlinuxs=$(find "$RPM_BUILD_DIR" -depth -maxdepth 3 -type f -name vmlinux -print -quit)
+	vmlinuxs=$(find "$RPM_BUILD_DIR" -depth -maxdepth 4 -type f -name vmlinux -print -quit)
 	vmlinuxd=./usr/lib/debug/lib/modules/$kver/vmlinux
 
 	if [ -f "$vmlinuxs" ]; then
 		install -pD -m644 "$vmlinuxs" "$vmlinuxd"
 		f=$vmlinuxd
 	else
-		Warning "vmlinux not found for -debuginfo"
+		Warning "vmlinux not found in $RPM_BUILD_DIR for -debuginfo"
 		exit
 	fi
 fi