cmsis-dap: add initial cmsis-dap support

This is based on work from:
https://github.com/TheShed/OpenOCD-CMSIS-DAP/tree/cmsis-dap

Main changes include moving over to using HIDAPI rather than libusb-1.0
and cleaning up to merge into master. Support for reset using srst has
also been added.

It has been tested on all the mbed boards as well as the Freedom board
from Freescale. These boards only implement SWD mode, however JTAG mode
has been tested with a Keil ULINK2 and a stm32 target - but requires a lot
more work.

Change-Id: I96d5ee1993bc9c0526219ab754c5aad3b55d812d
Signed-off-by: Spencer Oliver <spen@spen-soft.co.uk>
Signed-off-by: Andrey Yurovsky <yurovsky@gmail.com>
Reviewed-on: http://openocd.zylin.com/1542
Tested-by: jenkins

contrib/cross-build.sh

@@ -20,6 +20,7 @@
 #
 # Usage:
 # export LIBUSB1_SRC=/path/to/libusb-1.0
+# export HIDAPI_SRC=/path/to/hidapi
 # export OPENOCD_CONFIG="--enable-..."
 # cd /work/dir
 # /path/to/openocd/contrib/cross-build.sh <host-triplet>
@@ -36,13 +37,16 @@ WORK_DIR=$PWD
 ## Source code paths, customize as necessary
 : ${OPENOCD_SRC:="`dirname "$0"`/.."}
 : ${LIBUSB1_SRC:=/path/to/libusb}
+: ${HIDAPI_SRC:=/path/to/hidapi}
 
 OPENOCD_SRC=`readlink -m $OPENOCD_SRC`
 LIBUSB1_SRC=`readlink -m $LIBUSB1_SRC`
+HIDAPI_SRC=`readlink -m $HIDAPI_SRC`
 
 HOST_TRIPLET=$1
 BUILD_DIR=$WORK_DIR/$HOST_TRIPLET-build
 LIBUSB1_BUILD_DIR=$BUILD_DIR/libusb1
+HIDAPI_BUILD_DIR=$BUILD_DIR/hidapi
 OPENOCD_BUILD_DIR=$BUILD_DIR/openocd
 
 ## Root of host file tree
@@ -90,6 +94,17 @@ $LIBUSB1_CONFIG
 make
 make install DESTDIR=$SYSROOT
 
+# hidapi build & install into sysroot
+if [ -d $HIDAPI_SRC ] ; then
+  mkdir -p $HIDAPI_BUILD_DIR
+  cd $HIDAPI_BUILD_DIR
+  $HIDAPI_SRC/configure --build=`$HIDAPI_SRC/config.guess` --host=$HOST_TRIPLET \
+    --with-sysroot=$SYSROOT --prefix=$PREFIX \
+    $HIDAPI_CONFIG
+  make
+  make install DESTDIR=$SYSROOT
+fi
+
 # OpenOCD build & install into sysroot
 mkdir -p $OPENOCD_BUILD_DIR
 cd $OPENOCD_BUILD_DIR