Add optionals build configs for qemu upstream:
CONFIG_QEMUU_DEBUG for enable debug, disabled by default
CONFIG_QEMUU_SPICE for enable spice, disabled by default for now
Add to README requirements for spice enabled

Signed-off-by: Fabio Fantoni <fabio.fantoni@xxxxxxxxxx>

diff --git a/Config.mk b/Config.mk
index bc6be65..918aa7b 100644
--- a/Config.mk
+++ b/Config.mk
@@ -203,6 +203,8 @@ ETHERBOOT_NICS ?= rtl8139 8086100e
 CONFIG_OVMF ?= n
 CONFIG_ROMBIOS ?= y
 CONFIG_SEABIOS ?= y
+CONFIG_QEMUU_DEBUG ?= n
+CONFIG_QEMUU_SPICE ?= n
 
 # Specify which qemu-dm to use. This may be `ioemu' to use the old
 # Mercurial in-tree version, or a local directory, or a git URL.diff --git a/README b/README
index b15a59b..fdb5e3a 100644
--- a/README
+++ b/README
@@ -60,6 +60,8 @@ provided by your OS distributor:
     * 16-bit x86 assembler, loader and compiler (dev86 rpm or bin86 & bcc debs)
     * ACPI ASL compiler (iasl)
     * markdown
+    * if CONFIG_QEMUU_SPICE=y Dev of spice protocol (e.g. libspice-protocol-dev)
+      Dev of spice server (e.g. libspice-server-dev >=0.10)
 
 Second, you need to acquire a suitable kernel for use in domain 0. If
 possible you should use a kernel provided by your OS distributor. Ifdiff --git a/tools/Makefile b/tools/Makefile
index 6430bfb..eceecb2 100644
--- a/tools/Makefile
+++ b/tools/Makefile
@@ -87,6 +87,14 @@ IOEMU_CONFIGURE_CROSS ?= --cpu=$(XEN_TARGET_ARCH) \
 			 --interp-prefix=$(CROSS_SYS_ROOT)
 endif
 
+ifeq ($(CONFIG_QEMUU_DEBUG),y)
+QEMU_OPTIONAL_CONFIGS += --enable-debug
+endif
+
+ifeq ($(CONFIG_QEMUU_SPICE),y)
+QEMU_OPTIONAL_CONFIGS += --enable-spice
+endif
+
 QEMU_ROOT := $(shell if [ -d "$(CONFIG_QEMU)" ]; then echo "$(CONFIG_QEMU)"; else echo .; fi)
 ifneq ($(QEMU_ROOT),.)
 export QEMU_ROOT
@@ -158,6 +166,7 @@ subdir-all-qemu-xen-dir subdir-install-qemu-xen-dir: qemu-xen-dir-find
 		--disable-kvm \
 		--python=$(PYTHON) \
 		$(IOEMU_CONFIGURE_CROSS); \
+		$(QEMU_OPTIONAL_CONFIGS); \
 	$(MAKE) install
 
 subdir-clean-qemu-xen-dir: