Add libzip as dependency

CMakeLists.txt

@@ -210,6 +210,7 @@ IF(WITH_CORE)
   IF (WITH_GUI)
     FIND_PACKAGE(Qwt REQUIRED)
   ENDIF (WITH_GUI)
+  FIND_PACKAGE(LibZip REQUIRED)
 
   IF (WITH_INTERNAL_QEXTSERIALPORT)
     SET(QEXTSERIALPORT_INCLUDE_DIR ${CMAKE_SOURCE_DIR}/src/core/gps/qextserialport)

cmake/FindLibZip.cmake

@@ -0,0 +1,40 @@
+# CMake module to search for libzip
+#
+# Once done this will define
+#
+#  LIBZIP_FOUND - system has the zip library
+#  LIBZIP_INCLUDE_DIR - the zip include directory
+#  LIBZIP_LIBRARY - Link this to use the zip library
+#
+# Copyright (c) 2017, Paul Blottiere, <paul.blottiere@oslandia.com>
+#
+# Redistribution and use is allowed according to the terms of the BSD license.
+# For details see the accompanying COPYING-CMAKE-SCRIPTS file.
+
+FIND_PATH(LIBZIP_INCLUDE_DIR
+  zip.h
+  PATHS
+  /usr/local/include
+  /usr/include
+  "$ENV{LIB_DIR}/include"
+  "$ENV{INCLUDE}"
+  )
+
+FIND_LIBRARY(LIBZIP_LIBRARY
+  NAMES zip
+  PATHS
+  /usr/local/lib
+  /usr/lib
+  "$ENV{LIB_DIR}/lib"
+  "$ENV{LIB}"
+  )
+
+IF (LIBZIP_LIBRARY AND LIBZIP_INCLUDE_DIR)
+  SET(LIBZIP_FOUND TRUE)
+ENDIF (LIBZIP_LIBRARY AND LIBZIP_INCLUDE_DIR)
+
+IF (LIBZIP_FOUND)
+  MESSAGE(STATUS "Found libzip: ${LIBZIP_LIBRARY}")
+ELSE (LIPZIP_FOUND)
+  MESSAGE(FATAL_ERROR "Could not find libzip")
+ENDIF (LIBZIP_FOUND)