Add HIDAPI to build dependencies

.travis.yml

@@ -37,14 +37,17 @@ addons:
         - autopoint
         - faketime
         - libcmocka-dev
+        - libhidapi-dev
     homebrew:
         packages:
         - libusb
         - gettext
+        - cmocka
+        - hidapi
 
 # Ensure that build dependencies are available on OSX
 before_script:
-    - if [ "$TRAVIS_OS_NAME" = osx ]; then brew install libusb gettext cmocka ; fi
+    - if [ "$TRAVIS_OS_NAME" = osx ]; then brew install libusb gettext cmocka hidapi; fi
 
 # Enable parallel make
 env:

configure.ac

@@ -44,6 +44,11 @@ AC_SUBST([LIBUSB_LIBS])
 AC_SUBST([X52_PKG_VERSION], [0.1])
 AC_SUBST([X52_INCLUDE], ["-I \$(top_srcdir)/lib/libx52"])
 
+# Check for hidapi. This uses a different pkg-config file on Linux vs other
+# hosts, so check accordingly
+AM_COND_IF([LINUX], [hidapi_backend=hidapi-hidraw], [hidapi_backend=hidapi])
+AX_PKG_CHECK_MODULES([HIDAPI], [${hidapi_backend}], [], [have_hidapi=yes], [have_hidapi=no])
+
 # Check for pthreads
 ACX_PTHREAD