tools: add a generic config for native tools building

The motivation for this is to allow distributions to distribute all
possible tools in a generic way, avoiding the need of specific tools
building for each machine.

Especially on OpenEmbedded / Yocto Project ecosystem, it is very
common each BSP to end providing their specific tools when they need
to generate images for some SoC (e.g MX23 / MX28 in meta-freescale
case).

Using this, we can package the tools doing:

$: make tools-only_defconfig
$: make tools-only

Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
[trini: Add MAINTAINERS entry for myself, add to .travis.yml, make
U-Boot itself buildable to not trip up other frameworks]
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/.travis.yml b/.travis.yml
index fe2dfce..321fd79 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -336,6 +336,10 @@
     - name: "Check for configs without MAINTAINERS entry"
       script:
         - if [ `./tools/genboardscfg.py -f 2>&1 | wc -l` -ne 0 ]; then exit 1; fi
+    # Ensure host tools build
+    - name: "Build tools-only"
+      script:
+        - make tools-only_config tools-only -j$(nproc)
 
     # test/py
     - name: "test/py sandbox"
diff --git a/MAINTAINERS b/MAINTAINERS
index 0cec39c..0fb0898 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -719,5 +719,6 @@
 Q:	http://patchwork.ozlabs.org/project/uboot/list/
 S:	Maintained
 T:	git git://git.denx.de/u-boot.git
+F:	configs/tools-only_defconfig
 F:	*
 F:	*/
diff --git a/configs/tools-only_defconfig b/configs/tools-only_defconfig
new file mode 100644
index 0000000..fb06076
--- /dev/null
+++ b/configs/tools-only_defconfig
@@ -0,0 +1,24 @@
+CONFIG_SYS_TEXT_BASE=0
+CONFIG_ANDROID_BOOT_IMAGE=y
+CONFIG_FIT=y
+CONFIG_FIT_SIGNATURE=y
+# CONFIG_CMD_BOOTD is not set
+# CONFIG_CMD_BOOTM is not set
+# CONFIG_CMD_ELF is not set
+# CONFIG_CMD_DATE is not set
+CONFIG_OF_CONTROL=y
+CONFIG_OF_HOSTFILE=y
+CONFIG_DEFAULT_DEVICE_TREE="sandbox"
+# CONFIG_UDP_FUNCTION_FASTBOOT is not set
+CONFIG_SANDBOX_GPIO=y
+CONFIG_DM_I2C_COMPAT=y
+CONFIG_PCI=y
+CONFIG_DM_PCI=y
+CONFIG_PCI_SANDBOX=y
+CONFIG_DM_RTC=y
+CONFIG_SOUND=y
+CONFIG_SYSRESET=y
+# CONFIG_VIRTIO_MMIO is not set
+# CONFIG_VIRTIO_PCI is not set
+# CONFIG_VIRTIO_SANDBOX is not set
+# CONFIG_EFI_LOADER is not set
diff --git a/tools/Makefile b/tools/Makefile
index c26b631..2c4d91f 100644
--- a/tools/Makefile
+++ b/tools/Makefile
@@ -126,7 +126,7 @@
 fit_check_sign-objs   := $(dumpimage-mkimage-objs) fit_check_sign.o
 file2include-objs := file2include.o
 
-ifneq ($(CONFIG_MX23)$(CONFIG_MX28),)
+ifneq ($(CONFIG_MX23)$(CONFIG_MX28)$(CONFIG_FIT_SIGNATURE),)
 # Add CONFIG_MXS into host CFLAGS, so we can check whether or not register
 # the mxsimage support within tools/mxsimage.c .
 HOSTCFLAGS_mxsimage.o += -DCONFIG_MXS